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Utilizing advanced spatial collection and monitoring technologies: surveying topographical datasets with unmanned aerial systems

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Utilizing advanced spatial collection and monitoring technologies: surveying topographical datasets with unmanned aerial systems

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Utilizing Advanced Spatial Collection and Monitoring Technologies:
Surveying Topographical Datasets with Unmanned Aerial Systems

by

Charles R. Jurden, Jr.

A Thesis Presented to the
Faculty of the USC Graduate School
University of Southern California
In Partial Fulfillment of the
Requirements for the Degree
Master of Science
(Geographic Information Science and Technology)

May 2018

Copyright © 2018 by Charles R. Jurden, Jr.

To my family, Jennifer, Alexus, Zakary, Emma-Grace, and Mila Jade.

iv
Table of Contents
List of Figures ................................................................................................................................ vi
List of Tables ................................................................................................................................ vii
Acknowledgements ...................................................................................................................... viii
List of Abbreviations ..................................................................................................................... ix
Abstract ......................................................................................................................................... xii
Chapter 1 Introduction .................................................................................................................... 1
1.1. Motivation ...........................................................................................................................1
1.2. Data .....................................................................................................................................3
1.2.1 Study Areas ............................................................................................................4
1.3. Collections Methods ...........................................................................................................6
Chapter 2 Related Works ................................................................................................................ 9
2.1. Lineage ................................................................................................................................9
2.2.1 Data Use ...............................................................................................................10
2.2. History...............................................................................................................................10
2.3. Relative Research ..............................................................................................................11
2.4. Precision and Accuracy Analysis Methods .......................................................................13
2.4.1 Formula ................................................................................................................13
Chapter 3 Data and Methods......................................................................................................... 18
3.1. Comparative Data .............................................................................................................18
3.2. Pre-Flight Planning ...........................................................................................................18
3.3. Project Flight .....................................................................................................................21
3.3.1 Flight Parameters ..................................................................................................21
3.3.2 Study Areas ..........................................................................................................24
v
3.3.3 Scale and the Lens ................................................................................................25
3.3.4 Tallgrass Site Flight Pattern .................................................................................26
3.3.5 Asphalt Site Flight Pattern ...................................................................................28
3.3.6 Dickinson Site Flight Pattern ...............................................................................29
3.4. Data Extraction and Processing ........................................................................................29
3.5. Accuracies .........................................................................................................................31
Chapter 4 Results .......................................................................................................................... 37
4.1. Results Analysis ................................................................................................................37
4.2. Individual Site Results ......................................................................................................40
4.2.1 Asphalt Site ..........................................................................................................40
4.2.1 Dickinson Site ......................................................................................................41
4.2.3 Tallgrass Site ........................................................................................................43
4.3. Confidence Levels ............................................................................................................44
Chapter 5 Discussion and Conclusions ......................................................................................... 48
5.1. SWOT (Strengths Weaknesses Opportunities Threats) Analysis .....................................48
5.1.1 Strengths ...............................................................................................................48
5.1.2 Weaknesses ..........................................................................................................49
5.1.3 Opportunities ........................................................................................................50
5.1.4 Threats ..................................................................................................................50
5.2. Sources of Error and Problems .........................................................................................51
5.3. Future Improvements ........................................................................................................52
References ..................................................................................................................................... 55
Appendix A Tables and Maps ....................................................................................................... 61

vi
List of Figures
Figure 1 OGRIP LiDAR point cloud ............................................................................................ 2
Figure 2 Scale & focal length interepretation ............................................................................. 15
Figure 3 Trigonomic function of aerial triangulation .................................................................. 16
Figure 4 Flight parameters created in DJI GSP at the Tallgrass Site. ........................................... 20
Figure 5 Tallgrass GCP placement location ............................................................................... 27
Figure 6 Asphalt site volume map ............................................................................................... 68
Figure 7 Asphalt site contour map – P 1 ...................................................................................... 69
Figure 8 Asphalt site contour map – P 2 ...................................................................................... 70
Figure 9 Asphalt site contour map – P 3 ...................................................................................... 71
Figure 10 As-Built compilation report – Price Pad P 1 ............................................................... 72
Figure 11 As-Built compilation report – Price Pad P 2 ............................................................... 73
Figure 12 Tallgrass site As-built/UAS comparison map .............................................................. 74
Figure 13 LiDAR/LAS comparison chart 1 .................................................................................. 75
Figure 14 LiDAR/LAS comparison chart 2 .................................................................................. 76

vii
List of Tables
Table 1 GCP report for accuracy ................................................................................................. 25
Table 2 GCP comparison chart .................................................................................................... 32
Table 3 Inversion report ............................................................................................................... 32
Table 4 LiDAR report chart ......................................................................................................... 34
Table 5 Absolute camera and deviation uncertainties ................................................................. 38
Table 6 Relative geolocation variance report for the Asphalt site ............................................... 39
Table 7 Asphalt random samples ................................................................................................. 41
Table 8 Dickinson random samples ............................................................................................. 42
Table 9 Tallgrass random samples (A) ........................................................................................ 43
Table 10 Tallgrass random samples (B) ...................................................................................... 44
Table 11 Deviation report ............................................................................................................ 45
Table 12 Root Mean Square/Altitude relationship table .............................................................. 65
Table 13 USGS check shot point ................................................................................................. 65
Table 14 LAS points derived from UAS ..................................................................................... 66
Table 15 Data sources .................................................................................................................. 67

viii
Acknowledgements
I am grateful for the support of my family throughout this grand adventure. Through the
time that it has taken to complete this part of our journey, we have found struggles and the
patience to persevere, we found elations and imprinted them upon our hearts. I am thankful to the
staff of USC’s Dornsife for their guidance and unmatched skill in their disciplines. Fight on!

ix
List of Abbreviations
AGL Above Ground Level
ASPRS American Society for Photogrammetry and Remote Sensing
cm centimeter
C.I. Contour Interval
csv comma separated value
DEM Digital Elevation Model
DSM Digital Surface Model
DTM Digital Terrain Model
FAA Federal Aviation Administration
ft foot
GCP Ground Control Point
GIS Geographic information system
GISci Geographic information science
GNSS Global Navigation System
GPS Global Positioning System
x
GRD Ground Resolve Distance
GRS80 Geodetic Reference System 1989
GSD Ground Sampling Distance
HDOP Horizontal Dilution of Precision
in inch
INS Inertial Navigation System
jpg digital image (Joint Photographic Experts Group format)
LAS Laser file format (LiDAR exchange files)
LiDAR Light Detection and Ranging
m meter
Micro SD Micro Secure Digital data storage card
MPH Miles Per Hour
NAD83 North American Datum 1983
NAVD88 North American Vertical Datum 1988
ODOT Ohio Department of Transportation
OGRIP Ohio Geographically Referenced Information Program
xi
OSIP Ohio Statewide Imagery Program
P4 DJI Phantom 4
P4D Pix4D software
PDOP Position Dilution of Precision
px pixel
RMSE Root Mean Square Error
RPIC Remote Pilot in Charge
RTK Real-Time Kinematic
tif Tagged Image File
TIN Triangulated Irregular Network
UAS Unmanned Aerial System
USC University of Southern California
USGS United Stated Geological Survey
VDOP Vertical Dilution of Precision
VRS Virtual Reference System
XYZ Longitude – Latitude (or, Easting – Northing) and Vertical (respectively)
xii

Abstract
This study detailed the data collection, processing, and source comparison of DJI
Unmanned Aerial System (UAS) drone data from different examples of topographical datasets
for accuracy testing. Three datasets were chosen as they were characteristically different, these
terrains were those typically encountered while surveying in the energy industry and are
representative of terrain types encountered in the south Ohio area. More broadly they are
comparable with other terrain systems.
The system used to collect the UAS data consisted of a DJI Phantom 4 unmanned aerial
vehicle controlled by DJI Ground Station Pro on an iPad Pro that input and monitored flight
parameters. The processing used various software applications. These included Pix4D, which
was the photogrammetry software used to convert the data into georeferenced mosaics, models,
and point clouds. Additionally, Esri’s ArcGIS and Idrisi Terrset were also used in performing
analysis.
The data was then analyzed to find correlation to LiDAR and ground control to compare
elevation similarities. For the purpose of this study ground control points and LiDAR are
considered the trusted source of reference accuracy and precision. Accuracy was assessed against
the control material by inversion methods, geometry, and visual assessments. The testing
concluded cohesive data precision, accuracy, and detailed the process of creating remotely-
sensed materials and their conversion to geometrically accurate data.

1

Chapter 1 Introduction
Technological advances using drones in Unmanned Aerial Systems for spatial data
acquisition and the subsequent software processing programs that are used for topographical
surveying in large-scale mapping projects increase resource usability while maintaining accuracy
and precision. This research was directed at comparing the output of drone collected data to
aerial methods that are already a source of data trusted by mapping organizations. This work
evaluated the success of large-scale topographical projects.
1.1. Motivation
The test areas that were chosen and surveyed were sites that covered fifteen or less acres,
had different terrain types, and represented potential various stages in the construction phases of
the energy industry. Topographic data in the survey field is historically collected using time-
consuming, conventional measures that incorporate a total station, transit, level, or theodolite, or
with GPS technology. None of these methods have imagery (that helps the office technician or
processing agent) through providing an overview of surveyed land areas, minus a field book of
notes there are no cross-referenced ‘of the date surveyed’ materials. Online satellite imagery is
available, from sites such as Google Earth – but it is not up-to-date with the features that are
present on the day an area is surveyed. Many times, structures and/or features are new or absent
in the imagery, which ultimately renders these sources obsolete.
This study focused on the collection of this type of data using a drone (Unmanned Aerial
Systems [UAS]) remote sensing image capture and support software with the capacity to capture
precise and accurate photogrammetric data. This potentially may become the standard source for

2

data retrieval in future survey, as well as the context for producing digital elevation models
(DEM), point clouds, and Orthomosaic imagery.
1.1.2 LiDAR
LiDAR is the acronym for “Light Detection and Ranging.” Its technology uses lasers to
transmit and receive energy frequencies in phase and of narrow range to form images (Campbell
& Wynne, 2011). It is also referred to as airborne laser altimeter, where the echoes created by the
laser pulsing from its aerial host acquires point data by return measures. The return data is dense,
meaning that there is an immense amount of collected points containing XYZ data. X data is
longitudinal, Y is latitudinal, and Z data is height above the earth’s surface. The output is in the
form of point clouds, with the higher elevations having lighter colors to indicate Z, and gradually
darkening as Z lowers in elevation (see Figure 1).
Figure 1 OGRIP LiDAR point cloud.

3

1.2. Data
The Remote Pilot in Charge (or, RPIC) collected datasets from three sites using a drone.
They were then compared with those collected from LiDAR and as-generated as-built data.
These LiDAR data are considered “trusted” as being accurate according to the American Society
of Professional Remote Sensing (McGlone, Chris, 2014). ASPRS established Accuracy
Standards for Digital Geospatial Data and is considered the authority of survey standards for
aerially recorded and processed data. Processed data resulted in similar topographical output, and
the comparisons concluded cohesive data precision to that of geometrically accurate data.
This study defined advantages of automated digital photogrammetry by concluding that
the multi-scale applicability allowed the “creation of coherent standard grid-based digital
elevation models (DEMs) of consistent precision and at very high sampling rates, thus able to
record very detailed morphology” (Walstra, J., Chandler, J., Dixon, N., Dijkstra, T., n.d.).
In this research, the acquisition of drone related aerial photography used the following
considerations:
• Ground coverage – The areas of interest were completely covered by the stereoscopic
overlap area of the images, with extended spectral range that could detect wavelengths
beyond the typical human ability.
• Scale – The scale of the photographs determine what precision photo-coordinates were
measured and feature sizes were discerned.

4

• Digital Elevation Model (DEM) creation - The digital representation of terrain was
created from Digital Terrain Models (DSMs) processed to Digital Surface Models
(DSMs) and point clouds were created.
• Hardware and software performance – Observations were made into the processing
speeds and functionality of the elements of the UAS (as, the unit was a system comprised
of various machines), and how improvements could be made (Pix4D, 2017).
1.2.1 Study Areas
The three datasets that were collected were representative of the types of terrain that are
typically encountered when surveying large scale multi-acre properties. As well, the variables in
these areas supported construction processes of sectors in the energy industry. The first area was
a pipeline compressor pad constructed atop a hill, referred to in this thesis as the “Tallgrass
Compressor Site”, or (Tallgrass Site). It is a completed facility, housing five large compressor
engines in four housing units. The history of the site includes a preliminary topography that was
reformed prior to construction. A compressor site consists of several machines that are used to
increase pressure along a pipeline, thus enabling product to continue along the pipeline over
longer distances with higher pressure. It has multiple buildings and piping networks, masking
some areas which created the potential to lose sight of the ground and make measurement
difficult.
The second test site was an asphalt mixing plant with multiple stockpiles of rock –
referred to in this thesis as the “Asphalt Plant Site”, and was chosen because the area is
representative of sites that require stockpile area volume calculation. Different sectors of the

5

energy field use stockpiles. Coal mining stockpiles product, as did this asphalt plant. The piles
are used, and then replaced – creating a need for monitoring product. Others may use stockpiles
for “spoil”, which is dirt temporarily removed to clear for trenching. This flyover was used to
calculate the volumes of asphalt, which could then be stored in a GIS and compared with
quarterly usage to develop trends or monitor loss. The comparative dataset for this project was
LiDAR retrieved from the State of Ohio’s online data dump.
The third area was a small lake flyover that consisted of approximately 10 acres of lake
and land coupled with steep elevation changes. It was referred to in this report as the “Dickinson
Ranch Site”, and was used as a test subject for water reflectance and edge detection to be
processed through Idrisi. It was also characterized by the steep elevation changes and heavy
vegetation, which, in some instances, have caused incorrect elevation readings. This test region
explored various methods for alleviating this error.
The principal goal of this study was to present the output of the photogrammetric image
matching topographical dataset from the drone collection. These dataset formats compared
favorably with traditional methods of aerial point cloud collection did correlate as datasets of
accuracy with precision consistencies. The system used to collect the UAS data consisted of a
DJI Phantom 4 unmanned aerial vehicle controlled by DJI Ground Station Pro on an iPad Pro to
set flight parameters. The processing of the finished product used various software applications
including Pix4D. This software is used to convert the data into georeferenced mosaics, models,

6

and clouds. Esri ArcGIS ArcMap 10 was used to analyze the DEMs (in the form of DTM and
DSM). Idrisi Terrset was utilized in analyzing DEM raster sets for histogram accuracies.
As noted, three datasets were collected from a drone and compared with those collected
from trusted sources of satellite captured LiDAR. This thesis aimed at concluded that processing
the information collected from the UAS would result in equal or more accurate and precise
topographical output when compared to analysis data, and therefore create preference for
situations requiring aerial data in the energy sector for mapping, reporting, and planning.
1.3. Collections Methods
Accuracy, the difference between measured and actual value and precision, the difference
in the variation between multiple measures of the same object were required for data assessment.
Accuracy was not assumed based on programming defaults, but incorporated techniques
including ground control points collected with Trimble R8-3 GNSS survey-grade equipment in
the NAD 83, Ohio South coordinate system elevation data. From this data, the implementation of
Ground Control Points (GCP) measured from a different source than the aerial photography
ensured consistency. Ground control points add redundancy to data and provability to statistical
analysis. Typical surveying adjustment methods include the compass rule, transit rule, and least
squares rule. The compass rule adjusts for equal precision in angular and horizontal error. The
transit rule adjusts angular and horizontal errors, but expects that that horizontal angles are
measured with higher precision. The least squares method is statistical by nature, and uses
various standard deviation formulas to compute best-fit solutions. If any errors occurred in the
data when collecting the conventional-type information, the previously mentioned survey
adjustment corrections would be utilized.

7

The different datasets were cross-referenced with other sources at their corresponding
locations in the testing areas to compare results for consistency. The Compressor Site was
compared to data collected from an as-built survey completed in the beginning of 2015. The
Asphalt Plant Site was compared with LiDAR derived from the ohio.gov website
(ogrip.oit.ohio.gov, 2017). The Dickinson Site was compared with a ground survey using VRS
RTK GNSS GPS recorded in 2017.
The parameters used for the drone flights were consistent in overall pattern, meaning that
the flights were performed at two height patterns and used multiple ground control points spread
throughout the test area. The asphalt stockpile and the lake’s parameters were similar.
Data accuracy was measured against national standards, determined by horizontal and
vertical accuracy, where “accuracy is the degree of conformity with a standard or measure of
closeness to a value,” and precision was “the degree of refinement in the performance of an
operation,” (Caltrans, 2015). For the purposes of analysis, photogrammetry standards from the
USGS National Map Standards were used as well. According to the USGS orthoimagery
requirements at a typical large-scale project are:
1. One-meter ground sample rate;
2. Bit depth of 8-bits; and
3. Current within three years of the map publication date.
The American Society for Photogrammetry and Remote Sensing (McGlone, Chris, 2013)
categorically defines accuracy standards and definitions. The vertical and horizontal accuracies
of any data are required to be at the 95% confidence level. Confidence level is the “percentage of

8

points within a dataset that are estimated to meet the stated accuracy; e.g., accuracy reported at
the 95% confidence level means that 95% of the positions in the dataset will have an error with
respect to true ground position that are equal to or smaller than the reported accuracy value,”
(McGlone, Chris, 2013).
The Pix4D software generated a report that was used to determine the precision of the
drone data. It was compared to the previously mentioned standards and then cross-referenced to
the comparative data for precision/accuracy analysis.

9

Chapter 2 Related Work
This chapter briefly outlines the history of photogrammetry, and describes related work
by presenting the core calculation methods of aerial photogrammetry and comparing them with
semi-automated techniques used for aerial drone collections and the processing of the resulting
spatial data.
2.1. Lineage
The sum of the careful observations of generations of humanity have evolved spatial
analysis techniques to include precise, accurate, and accessible photogrammetry techniques in
digital formats. Advancement is not without history.
Initiative, ingenuity, and sacrifice prevail throughout the historical annals of
photogrammetry, and with notable characters. Gottfried Konecny described in his keynote
address in 1985 four cyclical developments in photogrammetry through an approximate 50-year
cycle (Konecny, 1985): (1) Plane Table; (2) Analog; (3) Analytic; and (4) Digital.
A fifth development could potentially be included as the craft blossoms. It is categorized
by the readily available data easily accessible by the masses. It is: (5) Information. Information is
historical. It serves to guide in establishing foundational work. The same processes used to
determine precisions in older photogrammetry techniques are still viable usable calculations.
Information is also innovative. It is the tools and materials needed for advancement. The growth
of drone photogrammetry is served by readily available information.

10

2.1.2 Data Use
The end-product for the UAS drone data collection is cartographic presentation. The
output is used in diverse ways, each situational by usage. Cartographic display includes
(Konecny, 1985): (1) Topography; (2) Location; (3) Base; (4) Volume; and (5) Flow.
Topographical maps show natural and manmade features, specifically those that are
representative of elevations and land formations. These maps use contour lines to show the
earth’s shape. Manmade features represented on these maps may include travel-ways,
hydrological areas, survey control, and vegetation type (USGS, 2017). These types of maps are
typically large scale (which is 1:10,000 to 1:25,000) if acquired from USGS yet can be as large
as needed.
Inset maps are typically maps that are used to represent an overall location of an area. In
the energy industry, inset maps are used to reference the larger representation. Similarly,
orthorectified images are often used as background images for display of collected or created
points and/or line-work in mapping. Drones can be utilized in the energy sector to further these
mapping elements by providing up-to-date images. Flow maps and volume maps are different in
that they provide rate information. In the energy sector they often relate to a watershed, and
potentially focus on environmental and/or construction planning or remediation.
2.2. History
Notable inventions throughout history have led to the development of the current
methods of retrieval, processing, and use of photogrammetric data. Leonardo da Vinci conceived
of a device that enlarged images through glass. Albrecht Duerer developed the mathematical

11

foundations of perspective geometry. It was further developed for use in photogrammetry by
Rudolf Sturms through the relationship of projective geometry and photogrammetry. Daguerre
continued the art by creating the photographic process of capturing images on a surface, called
the Daguerreotype (Doyle, 1964).
Plane table photogrammetry, conceived by Aime Laussedat used the same principles as
plane table surveying. Photographs were taken and placed by station according to resection and
redrawn upon mapping paper. The age of analog photogrammetry heralded the use of
stereoscopy and the airplane. Stereoscopy used dual images to create the perception of depth,
while air flight by airplane made more collection with larger imaging at smaller scale possible.
These bookmarks in history created the culmination of the combination of spatial analysis
techniques into a singular niche, and historically cultivating the science of photogrammetry.
The digital age is considered the current age of photogrammetry. It is the technique for
gathering digital imagery of objects to produce geometry with the information, including the
application of metadata. Analysis of raster images is used for calculation, creating digital models,
and for image backdrops for GIS visualization.
2.3. Relative Research
Surveying is the determination of positional data by collection or establishment. The
surveying industry benefits from the advancement of collection methods. Still in its infancy,
drone-use methods are an advancement in the capturing of necessary information including safer
methods, and comparable results at better speeds. Drone make efficient use of time and
resources, and establish an unmanned system capable of survey grade accuracy (Barry and

12

Coakley, n.d.). Topographic data in the survey field has been historically collected using time-
consuming, on-the-ground methods with transit or level, and grew to include in recent history,
Global Positioning Systems (DeGraeve and Smith, 2010).
Prior work using photogrammetry techniques are chronicled in the publication “Higher
Surveying” from Breed, Hosmer, and Bone which was first published in 1908, and again in
1962, (Chapters 4 – 6). This publication provides a history of the process of aerial photography,
including formulas that correlate the conventional calculation processes that were used to
compare with middle-period and current methods. This work is accompanied by the article “The
History of Photogrammetry” from the Center for Photogrammetric Training and penned by
Gottfried Konecny. Writings that were used as reference for surveying terms and techniques
were produced by Wolf and Ghilani’s “Elementary Surveying: An Introduction to Geomatics”
and Singh, Artman, Taylor, and Brinton’s “Basic Surveying – Theory and Practice.” These
works also serve to stress the importance of ground control parameters.
Current software practices include the processes and procedures for extrapolating data
from UAS and techniques for creating accurate deliverables with the help of reference manuals
(such as from Pix4D, ArcGIS, DJI Phantom 4, ArcGIS and AutoCAD). Additional writings of
ongoing work include Karabork, Yildiz, Yilmaz, and Yakar’s “Investigation of Accuracy for
Digital Elevation Models Generated with Different Methods in Photogrammetry,” Barry and
Coakley’s “Accuracy of UAV Photogrammetry Compared with Network RTK GPS,” and
Mitasova et al.’s “Raster based Analysis of Coastal Terrain Dynamics from Multitemporal
LiDAR Data.” These works focus on the integration of accuracy, precision, and repeatability,
which are the three elements of high order data collection and processing.

13

2.4. Precision and Accuracy Analysis Methods
There are no perfect measurements in surveying. All measurements consist, in some part,
of errors. They are inherent in personnel, equipment, and the environment. Errors compiled in
surveying data are adjusted through various methods of minimizing error propagation.
2.4.1 Formula
Repetition is the key to a successful analysis, specifically the ability of the data to be
analyzed repeatedly with the same results. Historically, with technology advances, data
collection from legacy and new systems, compared against each other, resulted in similar
precision. According to “Aerial Photography and Image Interpretation” (Third Edition) by David
P. Paine and James D. Kiser, scale and distance are measured, and are dependent relationally
according to several factors: (1) the height of the instrument recording the photos; (2) the
characteristics of the machine doing the recording: and (3) and environmental factors that
produce image coordinates.
Interpretation is explanation. Interpretive geometry is the “process of recognizing and
identifying objects and judging their significance through careful and systematic analysis”
(Philpot, 2012). There are two main categories of photographs, terrestrial and aerial. Of these
two interpretations, this photogrammetric effort focused on aerial. Aerial photographs are
categorically vertical, oblique, or an infusion of both. Vertical photographs are perpendicular to
the plane of capture, or most nearly so – with images slightly and advertently askew being
referred to as tilted. Oblique image capture consist of images that are either low oblique – for
example, recorded at a 30° angle off vertical which can be used to create 3D models – or, high

14

oblique – which are images that include a continuous field of view, that is – the horizon. All the
test subject’s gimbal pitch angles were set to -90°, which indicated that the camera was facing
straight down towards the ground, specifying that the pilot’s intentions were a flight pattern that
was vertical, also known as nadir.
Statistical analysis of the horizontal and vertical accuracies was contrived using RMSE
(root mean square error). Horizontal was assessed in the X, Y, and radial direction RMSE, while
vertical was assessed using Z factors only.
The RMSE formula used is written:
1. RMSE = �
1
n
� (xi(map)
−
n
i =1
xi(surveyed))
2
; and

2. Computation of Mean errors: X
�
=
1
( n)
∑ x
i
n
i =1

where xi is the i
th
error in the specified direction, n is the number of checkpoints tested, and I is
an integer ranging from 1 to n (McGlone, Chris, 2013).
RMSE report were generated from Pix4D, and were cross-referenced to the USGS data
standards, according to ASPRS Accuracy Standards for Digital Geospatial Data taken from the
online source (retrieved online September 2017).

15

Recall that the photo scale is determined by the formula S= F/H-h (see Figure 2). The
average height for flight for each of the test sites was 100 feet above ground level, and reiterating
that the AGL was in this test was initiated by the Phantom 4 from a base height of 0.00 ft, and by
machine specs concluding the focal length of the P4 as 24 mm (or, 0.07874 ft), and adjusted
according to the GPS point 203 collected from the Asphalt test site zenith of 1226.729’, and
averaging the recorded LAS test points extrapolated from the file (Ohio State Plane South, NAD
83 average elevation 1228.558 ft to the third decimal significant figure).
For processing output to be accurate, the real focal length must be computed. Real focal
length is:
Fr(mm) = (F35*Sw)/34.6
Figure 2 Scale and focal length interpretation.

16

where F35 = focal length that corresponds to the 35mm equivalent, Fr = real focal length, and
Sw = real sensor width, (Pix4D, 2017).
Photogrammetry solutions for accuracy and precision share similar characteristics to
ground surveying. Precision and accuracy are based on a statistical analysis of triangular
geometry, or the measurements and checks of angles in a triangle (Hallert, 1962). In such
circumstances, the determination of angles is that the quality of measured data (shown in Figure
3)
N = a sin z/sin y
where a is the length or distance from aerial to ground, z is the interior angle of the triangulation,
and y is the interior angle of the triangulation.
Furthermore, the geometric quality of N can be determined from the special law of error
propagation. This law measures the effects of uncertainties in a list of variables. Quality
Figure 3 Trigonometry function of aerial triangulation

17

conforms with the replication of observations, and the results are a subsequent decrease of the
average of the standard deviation. Adjustments are made accordingly, with least squares the
preferred method. The least squares method is a best fit method, determined by the squared
distance between data output and a regression line, and is recognized as using a solution that best
approximates a value based on its relationship to other values in a general linear model. In basic
terms, the sum of the measures divided by the number of measures is equal to the output.
Therefore, taking the sum of the distances contrived from each calculation point in the
photograph, creating best squares, and using that data in a standard deviation analysis
systematically reduces error and increases theoretical precision and accuracy.

18

Chapter 3 Data and Methods
This chapter describes of the methods used to plan, gather, and process the drone
collected data, which were then compared to Ohio OGRIP LiDAR as well as conventional
survey data.
3.1. Comparative Data
LiDAR collected by the Ohio Department of Transportation was downloaded from the
State’s site. According to ODOT the provided LiDAR data met the requirements of positioning
parameters, including vertical positioning using NAVD88 as orthometric height datum and
Geoid model as GEOID12A. The coordinate system was area dependent. These projects were in
the southern coordinate system of the state of Ohio. The map projection was Lambert Conformal
Conic, the reference frame was NAD83 (2011), and the ellipsoid was GRS80.
Vertical error in LiDAR is ground dependent. Higher density data provides more accurate
results. Because of LiDAR’s ability to create dense datasets, highly vegetated areas are more
likely to be recorded correctly because more points pass through the vegetation (McGlone, Chris,
2013). The State of Ohio certifies its data according to the ASPRS 2013 Positional Accuracy
Standards as accurate and precise imagery and elevation data.
3.2. Pre-Flight Planning
An RPIC is often contracted to record data in an area they are unfamiliar with. A preview
of the area is recommended for pre-flight planning purposes, and to avoid blind flying. In some

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instances, a digital preview of the area is acceptable as opposed to an in-the-field assessment.
Planning by opening popular online map applications such as Google or Bing Maps, inputting
the central position of the proposed flight area, and planning the flight pattern and GSP positions
will suffice. For most of the project sites surveyed, a preview of the area from the in-the-field
perspective was required to determine flight path and ground control positioning as up-to-date
imagery was unavailable.
The project’s site pre-flight planning was more than looking at the area of flight, it was
visualizing the spatial qualities of the area with intention. There were major considerations in the
layout and patterning assessments in the pre-flight planning process. Ground control, instrument
staging, route coverage planning, and safety precautions and assessments were among measured
constructs. Updated software, including firmware, was a requirement as well. Out-of-date
software could have caused fly-away, whereby the aircraft and control unit miscommunicate, and
the unit can proceed to fly erroneously, causing loss of machine and data. The weather check is
necessary to ensure that machinery is not water damaged, or data compromised due to
reflectance from precipitation or photographic consistency is unbalanced due to windy
conditions. Common standards when preparing for the flight are necessary to ensure that
precision and accuracy standards are met when completing the aerial survey.
Ground control were geographically referenced control points set inside the perimeter of
each site. They were used in the software in the processing phase as a geographically referenced
point used in the calibration of the orthomosaic photo set. They helped “tie-down” the survey.
Typically, software producers recommend a minimum of 3 or 4 GCP’s per project, but the
number is project site specific and large ranges in elevation characterize decisions as to number.

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The number of different images that share the same GCP in each of them is important as well,
because evenly placed GCSs help minimize error in scale and orientation, and redundancy
calculates into accuracy and precision.
The flight patterns are important as well. Efficient overlay, according to Dr. Abdullah of
Penn State University, is one that exhibits front and side overlap of 70% and 60% respectively
(Penn State University, 2016). While DJI GSP flight is automated, including pattern parameters,
the need to understand the reason the machine automated the pattern was important because in
planning overlap, speed, and other parameters are user defined (refer to Figure 4).
Setting up the flight pattern with fewer flight lines with less turns was the preferred
option. Computing the lines themselves consisted of taking the single image ground coverage
area and applying the flowing formula:
Figure 4 Flight parameters created in DJI GSP at the Tallgrass Site.

21

SP = IW x (100-SL)/100
where SP is the distance between flight lines, IW is the image coverage area, and SL is sidelap.
After which, front lap is calculated:
FLN = (W/SP) + 1
where FLN is the flight line number, W is width, and SP is the distance between flight lines.
After the number of flight lines was numbered, the number of photos needed could be calculated.
Airbase (which is the distance between two photos) must be calculated using the formula:
B= IC(H) x ((100-EL)/100)
where B is airbase, IC is image coverage, H is height, and EL is end lap. Then, the number of
images per flight is calculated using the formula:
NI = (L/B) + 1
where NI is the number of images, L is length, and B is the airbase (Abdullah, 2016).
3.3. Project Flight
3.3.1 Flight Parameters
While each site had project specific parameters, similarities existed overall that aided in
the formulation of patterning, including but not restricted to flight height, gimbal pitch, overlap
and, overall coverage bounds. Adhering to this patterning, the Asphalt site, the Tallgrass, and the
Dickinson sites each shared similar characteristics although each site had individual properties

22

that made them unique. Terrain features were different. The Asphalt site has a flat surface, but
has ground features with steep elevation differences that constantly change. These being the piles
of materials that were situated throughout the site. The Tallgrass site grounds have been
permanently modified, and elevation changes were altered to include a gradual sloping pad that
will not likely change in design in the future. The Dickinson site is an area with major contour
changes that move into a draw to collect water, and is prone to change due to watershed
processes. Yet, the drone could acquire data in these environments.
The drone calculated its flight height from an at-ground-level base and recorded it as 0.00
ft. This measurement system is based on wherever the unit records the base elevation as ‘0’ and
refers all other elevations higher or lower than the base as AGL or, Above Ground Level – which
can incidentally include negative elevations – which should be a consideration in planning. The
height of the instrument was then cross-referenced through the flight software (DJI GSP, in this
case), and calibrated to real coordinate values. The DJI Phantom 4 drone that was used for these
projects has an onboard GPS receiver. The receiver trilaterated the camera’s position, which
when relied upon alone to calculate geometry can accrue errors. In this case the iPad that housed
the DJI GSP program and controlled the aerial flight was connected to a continually transmitting
internet source routed through a Verizon MiFi, which created a third data-link with the machine
in-air and geographic reference. This connection created a VRS referencing system that reduced
flight errors to ± 1.2 inches vertical and/or horizontal error (Pix4D, 2017 and DJI, 2017).
The Phantom 4 Pro also uses the GPS/GLONASS satellite positioning system to measure
location. Barometric sensors in the drone kept the machine at a level altitude when flying. The
P4 barometer is a device that measures atmospheric pressure directly around the machine. The

23

machine also uses ultrasonic sensors. These sensors are designed to keep the machine from
bumping or crashing into objects on all sides. In the case of the P4, the proprietary sensor
mechanism is known as the Obstacle Sensing System. The steady altitude manufactured into the
positioning of the P4 secured accuracy by eliminating flight height error influx into data
acquisition.
While there are marked differences in the file formats used for UAS drone data when
compared to LiDAR or traditional survey photogrammetry, the base methods in flight data
collection have not changed. Flight patterns must be planned in a way that the area to be
surveyed by the Remote Pilot in Charge (RPIC) is done so in a manner that captures more of the
survey area than needed to ensure coverage. Over-coverage is desired. Photos are still
categorically oblique or vertical.
Obliques are created by adjusting the degree of the camera opposite nadir which is
considered perpendicular to the ground. Obliques are used in digital photogrammetry for 3D
modeling. Vertical data is collected when the camera angle was nadir, or perpendicular to the
ground. In some cases, oblique data is collected because of error in equipment or atmosphere.
Bad weather conditions such as high winds or the pilot’s inability to compensate for sharp turns
or tight quarters can create unwanted parallax. This is referred to as drift. The same error can be
reported when data is being attempted at oblique, and complications create unwanted results.
Such errors can be a result of crab, which is the drifting of the craft off course of the pre-planned
route.

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Nadir is the flight characteristic where the plumb perspective of a single source in the
orthomosaic, that being a single photograph, is a part of the whole “stitched” photograph. Photos
that are vertical and provide a well-defined side and front overlap are preferred when creating the
ortho, as image displacement can occur, and cause out of scale elements on post-processed data
output, and shifts in perspective observed from various views creates inaccuracy.
When the UAS pilot photographs an area, the machine takes multiple photographs. These
images must be arranged together to form a whole photo, called an orthomosaic (also referred to
as ortho in this thesis). A UAS ortho is georeferenced by GPS collected through the quad-copter
as well as through the collection of ground control points (GCPs). These GPS collected control
points need to be situated throughout a test site in such a way as to help eliminate errors in
calculation of position in the real world for vertical checks, that produced more accurate
elevation data as well as tools for reducing or eliminating draping error. Flight path is an integral
part in consistency in data collection, and consideration is given to include a high front (or,
forward) overlap and sidelap percentages to ensure no area is left unphotographed.
3.3.2 Pix4D Correlations
The adoption of the previously defined parameters recommended by ASPRS were
processed automatically through the Pix4D Desktop software, after quality assurances confirmed
that the input information was recorded correctly. The GCP report correlated survey quality
GNSS GPS data to the aerial data. Table 1 represents the singular accuracies for each control
point, as well as the Mean, Sigma, and RMS Errors of the data collectively. The Projection Error
column is the summation of the keypoint in each position relative to the GCP’s location. When

25

the keypoint’s position is correlated to that of the GCP it creates a re-projection. The Projection
Error is the sum of that error. The Verified/Marked column is created after the user marks the
position of each GCP in photos. In this assessment, these positions were clarified by indicating
this position in the file setup called the GCP editor.
Table 1 GCP report for error accuracy
Mean (ft) 0.000000 0.000000 0.000000
Sigma (ft) 1.245790 1.632082 1.903370
RMS Error (ft) 1.245790 1.632082 1.903370

According to the Pix4D manual, the RMS error in the GCP error accuracy report “will
take into account the systematic error,” and the “comparison of the RMS error and Sigma error
indicates a systematic error. Of the 3 indicators, the RMS Error is the most representative of the
error in the project since it (considers) both the mean error and the variance,” (Pix4D, 2017).
3.3.3 Scale and the Lens
Focal length and altitude affects each individual photograph, thereby potentially affecting
the orthomosaic. Focal length is defined as the distance measured from the center of the lens to
the focal point upon which the data is captured. It is relationally relevant to the ground data in
the formula and defined in the drawing provided previously in Figure 2, page 15.
Photo scale is the ratio of the distance between two points on a photo, in relation to their
position in real world. Map scale is the relationship of the distance between two points on a
photo, correlative to position in the real world. For example, simple scale describes an object that

26

is one inch on a photo from another object, and the same two objects are one hundred feet in the
real world then the scale is said to be 1:100. While photo scale and map scale are used similarly
in that both represent accuracy, both have marked differences in derivation.
Choosing the correct camera to record photography is elemental in creating precise and
accurate data. Detailed, aperture is the width of the opening of the shutter upon lens, and allows
light into the camera and onto the image recording surface, and is important – as is the width of
the lens itself (measured in millimeters) – in determining the focal capabilities of a camera.
Typical narrow width apertures and slow shutter speeds are better at capturing wide areas with
all the features in focus (the paradox being that a lens with a large aperture setting at high speed
shutter settings will only be focused on elements in the center of the focus). Because of the focal
length and aperture of the DJI Phantom 4’s proprietary camera is built with a 94° field of view,
and f/2.8 to f/11 autofocus at ± 1 meter, a focal length of 24 mm, and the ability to utilize a
narrow aperture that compliments the focal length to capture successive full field of view
images.
3.3.4 Tallgrass Site Flight Pattern
The Tallgrass Compressor site is home to several buildings, an expansive piping network,
as well as mufflers and blow-off stacks. These provide a sharp contrast to ground data. The GCP
layout procedure involved the placement of nine separate points in locations encircling the plant
perimeter. It is notable to acknowledge that no points were placed in the middle area. The area is
relatively flat. There are structures on the facility that prohibited extensive center-site placement.
Figure 5 displays the GCP positional location throughout the site. The blue circle related to the

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GCP’s coordinate Z position while the green represents AGL. The green segments relate
positional adjustments performed through P4D. Of the nine separate locations, each position was
cross-referenced with 3 -5 of the in-flight photos using the software’s GCP editor. All the points
were recorded using high-precision GPS recording equipment from Trimble in the prescribed
coordinate system. Ground control was set before the flight to ensure that the targets appear on
the photos. There were eight GCP’s on the site.
The Tallgrass site is the smallest, but with the most above-ground appurtenances of the
test areas. The area is approximately 11.5 acres. Therefore, the RPIC identified that it was
necessary to fly the site in four intervals from relative elevations in order to gather the best views
Figure 5 Tallgrass GCP placement location.

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of the piping in the area. Another flight at a higher elevation was also completed in one overall
pass to provide additional coverage for differential overlapping and referencing, as well as an
approach to avoid unwanted parallax errors. The DJI Ground Station Pro software was utilized to
perform the image capture. The flight parameters for one of the flight lines were indicated
previously in Figure 4, page20.
The compressor plant was flown at two heights, 106.0 ft and 164.0 ft AGL. The images
were compiled in one file and processed together. The purpose of multiple height flights is to
retrieve ground detail from a low flight and top of structure detail from higher elevation. The
resolution at 106.0 ft was 0.9 cm/px per meter, at 164 ft was 1.4 cm/px, and both elevations at
the flight speed of 10.5 mph.
3.3.5 Asphalt Site Flight Pattern
The Asphalt site needed to create a cohesive overall product by noting that troubled areas
needed more coverage This flight considered that by flying a pattern that was at least a ±60
percent side-overlap and ±70% front-overlap within whichever current flight-path the program
recorded, and rectified each separate segment of the flight, so that when combined to make a
single unit, also adhered to similar patterns.
The flight speed was ±10 mph to ensure that the machine’s flight was smooth and parallel
with the ground level, remembering that high winds can affect machine performance. The lower
altitude AGL for the lower segment of the survey was ± 100 feet. The resolution of the imagery
was 0.9 cm/px. This flight did not intend tilt (recalling that these are images derived from a
camera angle ±3° to 30° from ground perpendicular) or oblique photography (images derived

29

from camera angle ±35° to 55° from ground perpendicular) into the data in order to use the
output in stockpile volume calculations. The Asphalt site had nine GCP locations recorded
throughout the site.
3.3.6 Dickinson Site Flight Pattern
The drone recorded photos of the lake with a 73% front overlap ratio and a 60% side
overlap ratio. The gimbal pitch angle was at -90 °, indicating nadir vertical to ground. Initial
AGL (above ground level) was set constant at 103.4 feet with a camera resolution of 0.9 cm/px.
The second AGL was set constant at 201.0 feet with a camera resolution of 1.7 cm/px. There was
a difference in the AGL at the ±200 feet constant of the Dickinson site with an AGL at 203.6
feet. The course speed for the missions were set at 10.5 mph. The Dickinson site had five GCP’s
placed throughout the location.
3.4. Data Extraction and Processing
While in the planning phase, the number of photographs that is required to be recorded is
calculated to ensure sufficient information is available. The Phantom 4 Pro drone uses Micro
Secure Digital removable storage. Smaller sites require less space onto which information needs
to be stored, while testing, one to four-acre sites required at least a 32-gigabyte storage card.
Larger projects require more storage, as in the case of the Tallgrass site. The amount of space
required amounts to more than 50 gigabytes of space on two different 32-gigabyte cards, though
it is possible to use larger storage sizes. Integral Memory boasts a 512 GB storage microSD card.
There are several methods that can be used to extract the data from the drone. The
simplest and most widely-used method was to remove the Micro SD card and insert the card into

30

a laptop. The data recorded and stored on the card was transmitted into a folder for easy access
from Pix4D.
Reconnaissance was performed by researching the tedious details of where ground
control needed to be set, where to set the flight pattern and what type of data returns were needed
for the site mapping types. After which, the RPIC’s plan was put into action. The drone flew the
preset pattern, collecting the necessary aerial info. The mission was a success. After which, the
data was extracted and processed for use.
The image processing procedure in Pix4D was predominately automated after the system
design values are assigned. The downloaded tif images were uploaded into Pix4D, the image
properties were modified according to coordinate system, camera model, and accuracy.
Processing options according to desired output use were chosen, meaning P4D allowed user
processing input that included 3D maps and models, as well as multispectral and thermal
mapping. GCP locations in the various corresponding images were correlated by choosing the
same target in different photos so that the software could associate the images.
Pix4D class assignments were derived from machine-learned spectral analysis and
compared to a set of previously tested materials via a proprietary machine algorithm. From these,
elevation information was created (Becker, et al., 2017). This proprietary testing algorithm was
used to compute classifications geometrically and by color into buildings, terrain, high
vegetation, roads, human-made objects, or cars (Becker, et al., 2017), and into the last return,
which is supposedly the ground return that is the desired class for best precision data
extrapolation.

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Destructive interferences in image capture and processing played a part in point
classification. Sunlight – too much, or lack thereof – and ground objects with similar spectral
properties could inadvertently be misclassified (e.g., vegetation, water, or man-made objects).
Constructive interferences in the form of filters can be assimilated into the process – in initial
capture, and into pre- or post- to overcome these obstacles. Lens filters and flight time-of-day
planning choices reduced the chances of error in the field. Filters help reduce the effects of the
Sun’s UV rays onto data. Choosing a time-of day to fly when the sun is overhead reduces
shadow length, while early morning or evening casts more neutral light. Cloudy days produce
even light. Histogram creation and interpretation methods aided in classifying point data.
3.5. Accuracies
The process of confirming accuracies and precisions was further met by extrapolating
random elevation data from the LiDAR and drone refined DEM image and comparing the
elevation data to GCP control points in the area. Comparison panels on random photos cross-
referenced the Z of the nearby coordinates. The data was uploaded as a csv point file into
Trimble Office and an inverse report was created and zenith data was compared from the GCP
control point to each of the LAS test points.
The chart in Table 2 represents examples of the GCP’s that were chosen to compare the
LAS data against. The columns defined are “OID” is the point number assigned to each GCP,
chosen by the data collections person. The “Y”, “X”, and “Z” columns are representative of
location. The “Description” and “Location” columns briefly describe attributes of each point,
that being ground control target points specific to each test site.

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Table 2 GCP comparison chart
OID Y X Z DESCRIPTION LOCATION
2 747715.55 2331115.96 1178.65 TARGET DICKINSON
3 748059.06 2330924.42 1154.17 TARGET DICKINSON
101 705680.958 2318898.293 1227.434 TARGET TALLGRASS
104 705093.26 2319151.93 1231.191 TARGET TALLGRASS
203 754124.29 2360173.614 1226.729 TARGET ASPHALT
207 754451.195 2359674.005 1228.093 TARGET ASPHALT

The observations reproduced in Table 3 shows a portion of the LAS data with the nearby
point GCP 207 used as the comparative standard. The first column in the chart in Table 4 are the
GCPs used in this ground-truthing. Column 2 is the LAS point from which the vertical inverse
was derived. Columns 3 through 7 are the distance and bearing from which the GCP lays in
relation to the inverse point. OGRIP data output points per meter being fewer in number than the
UAS compiled data.
Table 3 Inversion report
From To
Geodetic
Azimuth
Ellipsoid
Distance
Grid
Azimuth
Grid
Distance
(US survey
foot)
Ground
Distance (US
survey foot)
Elevation
(US
survey
foot)
207 1007022 69°06'14" 0.552 69°06'14" 0.552 0.552 0.004
207 622296 332°00'37" 0.612 332°00'37" 0.612 0.612 0.064
207 517380 43°29'52" 1.43 43°29'52" 1.43 1.43 0.977
207 1007122 204°03'05" 0.459 204°03'05" 0.459 0.459 0.012
207 517302 232°53'25" 4.971 232°53'25" 4.971 4.971 0.727
207 518614 348°10'10" 9.175 348°10'10" 9.175 9.175 1.007

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Inversion in the surveying profession is the process by which a set of point coordinate
values is measured against another set. This is relational. The measure is initiated from a
common monument, and measured to variable instances, and by inversing a set of objects against
a standard enables individuals to derive deviation. The inverse method used herein employed
various points inversed to the known position of GCP 207 that determined vertical consistency.
Trilinear interpolation was the fundamental basis of this coordinate inversion. It is like bilinear
interpolation because it uses coordinate geometry to calculate grid distance and bearing
differences, but also considers the zenith, or vertical differences in the calculation.
According to Mitasova et al. while confirming per-cell statistical analysis of LiDAR data,
that higher point densities created terrain oversampling, yet not necessarily to the negative effect,
but “provided excellent representation of sharp edges and breaklines,” which are primary
datasets that topographical mapping relies on. Furthermore, the referenced research concluded
that LiDAR data shifted due to terrain change. These conclusions, although based on coastal
change are relatable findings in the energy industry’s pipeline services because the movement of
the natural grade and terrain coverage influences topsoil characteristics.
Observations based on data from Table 4 which represents the points that were randomly
chosen from the OGRIP LiDAR tiles. The “POINT_RECORD” column represents the assigned
return point number in each tile. The intensity is the return strength collected from each point on
the reflectivity of the object struck. Additionally, the reflectivity is the wavelength function
determined by object composition, (Esri, 2017). The “CLASS_CODE” column represents the
return classification code. In these cases, all returns were “2”, indicating “Ground” – also
referred to as last return. The “X”, “Y”, and “Z” columns are the location data. The

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“GPS_TIME” column represents the collection time of the LiDAR. The time was determined
using OGRIP website information. The tiles for this project are from the 2014 OSIP data source
(Ohio.gov, 2017).
Table 4 LiDAR report chart
PNT
RCRD
INTENSITY NO
RTRNS
CLASS
CODE
X Y Z GPS TIME LAS REF
323663 157 1 2 2331118.5 747713.38 1179.2 60814.988 s2330745
322767 173 1 2 2331111.3 747722.5 1178.77 60814.956 s2330745
323664 171 1 2 2331109.9 747714.34 1180.2 60814.988 s2330745
296348 61 1 2 2330926.2 748061.54 1149.19 60813.683 s2330745
296347 144 1 2 2330917.8 748062.37 1149.71 60813.716 s2330745
297177 80 1 2 2330924.9 748052.85 1150.5 60813.716 s2330745
517380 158 1 2 2359675 754452.23 1229.07 343955.14 s2355750
517302 204 1 2 2359670 754448.2 1228.82 343955.13 s2355750
518614 82 1 2 2359672.1 754460.18 1229.1 343955.18 s2355750
150418 128 1 2 2360174.4 754121.62 1226.14 341947.31 s2355750
149344 180 1 2 2360177.9 754130.16 1226.17 341947.28 s2355750
149343 195 1 2 2360170.2 754131.67 1226.65 341947.28 s2355750
652271 207 1 2 2319150.1 705097.4 1229.95 236034.27 s2315705
652272 180 1 2 2319160.1 705095.19 1230.15 236034.27 s2315705
651957 189 1 2 2319148.4 705101.44 1230.2 236034.25 s2315705
628767 212 1 2 2318899.7 705682.33 1219.49 236032.13 s2315705
628766 209 1 2 2318891.1 705684.5 1220.63 236032.13 s2315705
629042 183 1 2 2318900 705675.2 1220.54 236032.16 s2315705

Image resolution per-pixel was a determining factor in precision assessment. The image
resolution in digital photogrammetry is important, because the precision in scale is relationally
determined based on the resolution of the image. The OGRIP data output is 6 in pixel resolution,
with an 8-bit RGB rectified image producing a 2.5 ft DEM. In comparison, the data produced by
the UAS and Pix4D was a 2 cm pixel resolution, 8 bit RGB image producing a ground sampling

35

distance (GSD) average of approximately ± 1 cm per meter (although 16 bit input/output is
possible).
Scale was important in the assessment of accuracy. It was determined by calculation
adhering to standard requirements. Spatial representation was indicative of user need. Client
tailored mapping in the energy industry is commonly tailored to client requests and requirements.
Knowing that the produced imagery is in digital format, and is represented in pixels, the pixels
were analyzed to produce Ground Resolve Distance – which is the primary measure of spatial
resolution, and are the smallest measurable distance on the image, (Campbell & Wynne, 2011).
The pixels were dissected, and GRD resolution translated by the formula GRD = H/(f)*(R)
where GRD is the Ground Resolve Distance, H is the flying altitude above terrain, f is the focal
length, and R is the system’s resolution (Campbell and Wynne, 2011). This measure is an
important interpretation of the purposing of the imagery.
Ground Sampling Distance is the “distance between two consecutive points on the
ground (and) influences the accuracy and quality of the final results” in precision of the Pix 4D
data output (Pix4D, 2017). This created a point cloud that was denser than the OGRIP LAS, with
one testing sample a 20:1 UAS to OGRIP point ratio. Ground sampling distance is calculated:
Dw = (imW*GSD)/100
where Dw = distance covered on the ground per image (m) by width, imW = image width, and
GSD = desired (required) Ground Sampling Distance (cm/px), (Pix4D, 2017).

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Photo scale is used relationally with map scale to determine overall scale for comparative
analysis. Map scale is defined as the scale of the photo divided by scale of the map equals the
map distance divided by the photo distance, or SP/SM = MD/PD. This relationship was
important in assessing accuracy comparisons, as all scales should be equivalent, as unequal
outcome indicates error.
Drones provide visuals captured at hover, and equipped with the ability to rapidly store
data. The collection methods are relative intrinsically to the data accuracy and precision. When
techniques that are made provable are utilized according to outlined specifications, favorable
results incur.

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Chapter 4 Results
This chapter outlines the results and comparisons with USGS data that is certified by the
ASPRS as precise and reliable information.
4.1. Results Analysis
Replicated and repeated measurements are different. Both are important in accuracy
representation. Utilizing RMSE calculation and addressing elevations accuracy of the produced
DEM, the RMS calculated differences between field elevation points and elevations that are
obtained from points of DEM by interpolation produced consistent numbers. “The image
correlation and the automatic derivation of a DEM can also be used as starting for the generation
of digital orthophoto,” (Karabork, et al, 2004). Karabork iterates data matches by calculation and
grid. Results are approximately the same (Karabork, et al, 2004). Results remind that replicated
measurements are created in one place in one period, and repeated measurements are those that
are taken at different time periods.
Furthermore, the standard deviation comparison with the data gathered and compiled in
maps, agreed with the statistical analysis performed by the processing software and correlated
with ASPRS standards. (It should be noted that the calculations were based on a testing area that
was variable in nature, and the most desirable results were calculated in controlled environments,
such as a perfectly flat area with minimal environmental interferences, such as high winds,
barometric flux, or high solar reflectance).

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The data in Table 5 shows the typical absolute camera position and orientation
uncertainties of the Dickinson Site. This excerpt of the report was typical to other reports
generated on the other test site projects. It is used to verify that the mean error (average error in
each direction – X, Y, Z), and sigma (standard deviation of the error in each direction – X, Y, Z)
were of acceptable return. X Y Z are the cartesian equivalent of longitude, latitude, and zenith of
a measurement, respectfully. Omega is the rotation of the output around the X-axis. Phi is the
rotation around the Y-axis. Kappa represents the rotation around the Z-axis. Differences in data
that result in unusable errors are determined by the output. In this case, the averages resulted in
an overall Sigma error of less than a tenth in the X and Y quadrants and about three inches error
in the overall vertical measurements in Z.
Table 5 Absolute camera and deviation uncertainties

X (ft) Y (ft) Z (ft) Omega (degree) Phi (degree) Kappa (degree)
Mean 0.23 0.22 0.48 0.043 0.052 0.015
Sigma 0.06 0.06 0.14 0.006 0.014 0.006

Furthermore, according to Mitasova, et al. that, application dependent, “…various
functions can be used, from simple statistics, such as mean, median, mode, minimum, maximum,
standard deviation, and diversity, to more complex relationships, such as linear regression slope,
offset, and coefficient of determination, computed for each cell. The temporal aspect of terrain
evolution can be analyzed using a map that represents the time when the given cell was at its
lowest elevation and a map representing the time when each cell was at its highest elevation,”

39

(Mitasova, et al, 2009). For the purposes of this study, simple statistical observations calculating
the mean averages of a set of observed points as inversed to a GCP were administered.
The results in Table 6 were representative of the overall accuracy of the geolocation of
the photographs. The numbers verify that 99.38% of photographs used were within ± 1 foot, and
all were within ± 2 and 3 feet, verifying that the software verified data results in high-order data
accuracy.
Table 6 Relative geolocation variance report for the Asphalt site
Relative Geolocation Error Images X [%] Images Y [%] Images Z [%]
[-1.00, 1.00] 99.38 100.00 99.07
[-2.00, 2.00] 100.00 100.00 100.00
[-3.00, 3.00] 100.00 100.00 100.00
Mean of Geolocation Accuracy (ft) 5.00 5.00 10.00
Sigma of Geolocation Accuracy (ft) 0.00 0.00 0.00
Geolocation Orientational Variance RMS [degree]
Omega 0.96
Phi 0.58
Kappa 5.27

Additionally, Mitsova, et al. iterates the importance of GPS accuracy implementation in
precision discovery, as in the case of this report. The GCP GPS data, when used as reference for
reporting. They write that “the accuracy of the RTK GPS survey along the (survey area) was
sufficiently higher than the published accuracy of the LiDAR surveys…making the RTK GPS
data suitable for assessment of the actual LiDAR data accuracy,” (Mitasova et al, 2009). As
mentioned previously, similar observations were created when comparing LAS points derived
from the drone by inversion to the GCP and the LAS derived from OGRIP.

40

4.2. Individual Site Results
4.2.1 Asphalt Site
The Asphalt site data processing resulted in an average ground sampling distance of 0.82
cm/0.32 in in the covered 14.8164 acres. Recall that ground sampling distance is the linear
distance between two measured pixels on the ground. The larger the GSD, the less resolution an
image or data has (Pix4D, 2017). There were 9,921 calibrated 2D matches per image with 10
GCPs with a mean RMS error of 0.051 ft. The absolute camera position and orientation
uncertainties mean (average) in the XYZ were 0.029, 0.026, and 0.114, respectively. The mean
omega, phi, and kappa – (3D accuracy) were 0.006, 0.009, and 0.003 respectively. The absolute
camera position and orientation uncertainties sigma (standard deviation) in the XYZ were 0.007,
0.007, and 0.033, respectively. The sigma omega, phi, and kappa – (3D accuracy) were 0.002,
0.003, and 0.001, respectively.
There were 5,059,956 2D keypoint observations in the bundle block adjustment, with a
mean average of 30320 keypoints per image, a mean projection error of 0.155, and 9,921
matched keypoints per image, indicating the number of matching points that the software can use
to assess 3D information in each image.
Ground control point accuracy in the XY/Z parameters were 0.020/0.020. The mean error
of the X was 0.001849, the sigma of the X error was 0.065245, and the RMSE of the X was
0.065271. The mean error of the Y was -0.003252, the sigma of the Y error was 0.066500, and
the RMSE of the Y was 0.066580. The mean error of the Z was 0.006644, the sigma of the Z
error was 0.023135, and the RMSE of the Z was 0.024070.

41

Random samples taken from the LAS data at the Asphalt site derived around GCP point
208 indicates that there is an Z mean of 1230.578 ft elevation with average deviation of the Z
mean of 0.086667. In contrast, there is a vertical difference of 2.2170 between the GCP and
OGRIP LiDAR data (reference Table 7).
Table 7 Asphalt random samples
OID Y X Z DESCRIPTION
208 754285.301 2359710.95 1230.703 TARGET
1544815 754285.376 2359710.805 1230.405 LAS
1206500 754285.264 2359711.104 1230.72 LAS
805391 754284.911 2359710.797 1230.61 LAS
496606 754285.87 2359709.06 1232.92 LIDAR

Z Mean: 1230.578333

Z SD: 0.086666667

4.2.2 Dickinson Site
The Dickinson site data processing resulted in an average ground sampling distance of
1.03 cm/0.4 in in the covered 13.5705 acres. There was a median of 5,876 calibrated 2D matches
per image, with five GCPs and a mean RMSE of 0.082 ft. The absolute camera position and
orientation uncertainties mean (average) in the XYZ were 0.068, 0.063, and 0.121, respectively.
The mean omega, phi, and kappa – (3D accuracy) were 0.011, 0.015, and 0.004, respectively.
The absolute camera position and orientation uncertainties sigma (standard deviation) in the

42

XYZ were 0.019, 0.018, and 0.037, respectively. The sigma omega, phi, and kappa – (3D
accuracy) were 0.003, 0.004, and 0.002, respectively. There were 2,222,381 2D keypoint
observations in the bundle block adjustment, with a mean average of 46,624 keypoints per
image, a mean projection error (pixels) of 0.158, and 5,876 matched keypoints per image.
Ground control point accuracy in the XY/Z parameters were 0.020/0.020. The mean error
of the X was 0.011172, the sigma of the X error was 0.075243, and the RMSE of the X was
0.076068. The mean error of the Y was -0.013287, the sigma of the Y error was 0.072070, and
the RMSE of the Y was 0.073284. The mean error of the Z was 0.015463, the sigma of the Z
error was 0.100630, and the RMSE of the Z was 0.101811.
Random samples taken from the LAS data at the Dickinson site derived around GCP
point 3 indicates that there is a Z mean of 1154.15 ft elevation with an average deviation of the Z
mean of 0.0220 (reference Table 8).
Table 8 Dickinson random samples
OID Y X Z DESCRIPTION
3 748059.064 2330924.416 1154.171 TARGET
483030 748058.894 2330923.95 1154.181 LAS
94555 748059.542 2330924.655 1154.106 LAS
32067 748058.792 2330925.213 1154.163 LAS
296348 748061.53 2330926.07 1149.19 LIDAR

Z Mean: 1154.15

Z SD: 0.022

43

4.2.3 Tallgrass Site
The Tallgrass site data processing resulted in an average ground sampling distance of
1.86 cm/0.73 in in the covered 7.6879 acres. There were 3,920 calibrated matches per image with
nine GCPs with a mean RMSE of 0.009 ft. The absolute camera position and orientation
uncertainties mean (average) in the XYZ were 0.387, 0.481, and 5.964, respectively. The mean
omega, phi, and kappa – (3D accuracy) were 0.043, 0.049, and 0.009, respectively. The absolute
camera position and orientation uncertainties sigma (standard deviation) in the XYZ were 0.064,
0.021, and 0.106, respectively. The sigma omega, phi, and kappa – (3D accuracy) were 0.007,
0.020, and 0.006, respectively. There were 32,748 2D keypoint observations in the bundle block
adjustment, with a mean average of 3,920 keypoints per image, and 648 matched keypoints per
image.
Random samples taken from the LAS data at the Tallgrass site (A) derived around GCP
point 109 indicates that there is a Z mean of 1225.172667 ft elevation with an average deviation
of 0.055667. (reference Table 9).
Table 9 Tallgrass random samples (A)
OID Y X Z DESCRIPTION
109 705265.124 2318852.466 1225.284 TARGET
3326 705265.754 2318853.633 1225.154 LAS
980 705258.406 2318853.791 1225.08 LAS

Z Mean: 1225.172667

Z SD: 0.055666667

44

Ground control point accuracy in the XY/Z parameters were 0.020/0.020. The mean error
of the X was -0.000821, the sigma of the X error was 0.004411, and the RMSE of the X was
0.004487. The mean error of the Y was -0.002522, the sigma of the Y error was 0.006841, and
the RMSE of the Y was 0.007291. The mean error of the Z was 0.007173, the sigma of the Z
error was 0.017892, and the RMSE of the Z was 0.019276.
Random samples taken from the LAS data at the Tallgrass site (B) derived around GCP
point 3 indicates that there is a Z mean of 1154.15 ft elevation with an average deviation of the Z
mean of 0.093. Visual assessment was performed by contriving building position cross-
referenced with as-built (reference Table 10)
Table 10 Tallgrass random samples (B)
OID Y X Z DESCRIPTION
106 2318991.437 704757.168 1228.376 TARGET
10362 704756.878 2318994.019 1228.627 LAS
5521 704762.027 2318987.276 1228.32 LAS

Z Mean: 1228.441

Z SD: 0.093

4.3. Confidence Levels
The hypothesis confidence level was reportedly a ± 98%. Samples derived from the LAS
and compared to GCP, as well as data tested in Pix4D’s statistical computations agreed with this
conclusion. Observed samples tested randomly with deviation calculations as noted in Table 7

45

appeared to be similarly accurate. A rasterized vector derived from the DEM and the subsequent
histogram of the vertical data derived from Terrset also agreed with the data output in Pix4D,
and as observed by contour line generation visual comparison.
Table 11 Deviation report
POINT RECORD Y X Z PARENT LOCATION A Sample
150419 754123.146 2360166.87 1226.33 s2360750
844333 754123.949 2360165.654 1226.517 Asphalt Results Tracks 2
817224 754122.973 2360168.931 1226.495 Asphalt Results Tracks 2
150435 754120.303 2360165.437 1226.56 s2360750

Average of the samples 1226.4755

Average deviation of the samples 0.07275
POINT RECORD Y X Z PARENT LOCATION B Sample
61994 747760.881 2330755.766 1212.1 s2330745
701060 747760.291 2330753.544 1212.553 Dickinson Results Tracks 2
701164 747763.225 2330753.822 1212.487 Dickinson Results Tracks 2
701252 747763.225 2330758.613 1212.067 Dickinson Results Tracks 2

Average of the samples 1212.30175

Average deviation of the samples 0.21825

Considerations were taken to avoid a null hypothesis by avoiding contamination of the
test data. The current test statistics rejected the null hypothesis, but more random sampling was
needed to conclude irrefutable results. The implications derived from the analysis of the

46

information are that the random sampling of the drone LAS data was a part of the expected
population. The conclusion of this report is that Pix4D can create a point cloud that is similar in
vertical output as LiDAR, and meets or exceeds ASPRS confidence levels.
The OGRIP data download was expected to, and did meet and/or exceed horizontal and
vertical accuracy standards. Horizontal accuracies for maps represented in a scale of larger than
1:20,000 specify they are not allowed to have more than 10% of well-defined points with an
error of more than 1/30 inch as measured on the published scale. Maps with smaller scales than
1:20,000 are allowed 1/50

inch (Caltrans, 2012). Similarly, vertical accuracies require no more
than 10% of elevations can be in error by more than one-half of a contour interval, (Caltrans,
2012). LiDAR downloaded from Ohio’s data vault met the parameters of page A9 of the ASPRS
report of Photogrammetric Engineering and Remote Sensing, more specifically the Annex C,
Accuracy Testing and Reporting Guidelines on page A18 (ASPRS, 2015). The report continues
by describing that errors in LiDAR are a result of GNSS positional errors, INS (inertial
navigation systems) angular error, and flying altitude. Table 4 is the expected error in horizontal
data (RMSE) in terms of altitude (ASPRS, 2015), and can be scaled relatively into any project’s
parameters. Each of the testing areas produced the same results, that being contour data produced
from both sets of data and measured between each other are consistent in elevation one to the
other, as well as vertical point data being within the ASPRS standards using a 95% confidence
level.
Additional, referring to Table 6, page 36 we infer calculations derived from column four,
six, and seven shows that 67% of the points were within two feet of the GCP test point, whereas
the other ±33% were between ± 5 to 10 feet. It is noted that this is typical when comparing the

47

two LAS datasets, as the data derived from the drone proved far denser in point composition than
the OGRIP LAS data. This is due to the OGRIP data output points per meter being fewer in
number than the UAS compiled data. Visual comparison of the one square meter testing further
confirmed compared point density.
It was pertinent to keep in consideration in the testing parameters that systematic errors
were unavoidable, but typically follow fixed predictable patterns. The specific values that were
accepted as accurate from the calculations varied from project to project, but remembering that
ASPRS designated that there be less than a 25% error between the mean output and specified
RMSE. While Pix4D calculates the accuracy with automation, it is important to understand the
process by which errors occur so that errors can be detected and corrected. The horizontal
accuracy that was compared by planimetric coordinates (specifically, OH83-NF, which is Ohio
South State Plane coordinates on the NAD 83 datum grid), and additional vertical datum from
USGS monumentation and/or previously verified monumentation. Low-confidence areas were
also used in consideration, and ASPRS digital data guidelines that indicate these areas be
developed into polygons and results and reasonings explained in the metadata (ASPRS, 2015).

48

Chapter 5 Discussion and Conclusions
The FAA’s change in regulation to allow the acquisition of UAS drone commercial
licensure has yet to reach its anniversary date to which its initial class must apply for license
reissue. The commercial drone data collection industry is still in its infancy, but the ability of the
innate perception of spatial data planning, the visual conception of a project rigorously processed
competently through credible resources, and the material cross-referenced against dependable
sources can create desirable, usable data output. This section summarizes the data collected,
processed, and how the subsequent results affect the scope of the project.
5.1. SWOT (Strengths Weaknesses Opportunities Threats) Analysis
The SWOT for UAS drone technology is noticeably intertwined. The recently changed
FAA regulations created rapid advancement in the use of these systems as a mode of data
collection but not without consequences.
5.1.1 Strengths
There are several key strengths to the use of UAS drones to capture aerial images. The
initial prospect is described in this thesis, that being the ability of the system to create reliable
data that can be used in a variety of mapping and analysis projects. The accurate point clouds
derived from drones can depict topographical data used for construction planning and monitoring
of sites, equipment and appurtenances. The imagery derived can be used as visual aids in
planning as well as in situations where recent photos are a requirement, as in the case of

49

ALTA/NSPS land surveys, where up-to-date imagery is attached to finalized plats for visual
proofing in documentation.
The Phantom 4 machine and its controlling software is user-friendly, and takes a
minimum amount of training to acquire data on a mission. The software can be learned in
minutes. The drone comes equipped with a pre-set amateur parameter in the form of collision
avoidance settings, that when followed correctly keep an inexperienced user from colliding with
foreign objects
The data can be used in a variety of software. There are multiple outputs of the processed
data. The tif images can be used in programs like Terrset or QGIS and stitched together in a
mosaic manually and the topographical information analyzed. Other programs, such as Pix4D
used in this project, have multiple output formats including the DSM and DTM formats,
georeferenced Orthomosaic, contours, point cloud, mesh, volume calculations, and quality
reports.
5.1.2 Weaknesses
One of the major weaknesses found using the system is an adverse result from the UAS
drone’s strength in the form of its ease of use. The system’s focus on beginning RPICs in a
quickly growing industry opens doors that possibly should not be opened, which can result in the
proverbial Pandora’s Box. Prospective users who have little or no training in surveying or spatial
analysis collect data without knowing the accuracy or inaccuracy of the output data. The open-
door policy of the new technology fosters growth, as well as error. Additionally, the data output
has not been considered ‘certifiable’ by many in the surveying profession.

50

The quality of the Phantom 4 Pro is at a the low-end of professional grade, and while it
works well for academic purposes and less experienced RPICs the machine’s limited capabilities
are obvious to experienced users. The device cannot change camera types because the gimbal is
not interchangeable. The payload is low-weight, so attaching other types of sensors or
mechanisms to it were not recommended by the manufacturer at the time of this research.
5.1.3 Opportunities
There are many opportunities, including the production of the aforementioned
topographical data and photographic imagery, that are available. There is also the UAS ability to
perform visual inspection. The photography from this data type can be also be extracted with
Pix4D and used in the creation of 3D imagery. The technology houses formats that include the
sciences of thermal and magnetic sensing collection and inspection, which are all applicable
formats used in the energy industry.
5.1.4 Threats
Deviation is the threat to the energy industry. Deviating from sound collection methods
threatens the accuracy of data. Deviating from proven processing techniques may produce
unusable output. Deviating from FAA rules and regulations makes for unregulated flying
conditions that may be unsafe and counterproductive.
Users who fail to adhere to the fundamental techniques of spatial data collection and
processing may create erroneous data output, threatening the science’s credibility. If enough bad
data is produced, then the possibility of growing distrust in the industry is greater and will

51

threaten its growth. Additionally, failure to comply with FAA regulations will create more
regulations, stifling growth. Adversely and consequently, the FAA’s inability to monitor the
growth rate of new users can introduce too many new users into the field, the influx of new users
could potentially cause the market value to drop.
5.2. Sources of Error and Problems
The drone and machine software processes proved reliable in most instances when
firmware was updated, and maintenance kept regular. There were issues that were encountered
recording and processing these three sites of the project. Sources of human or machine
processing and collections error include: unforeseen or uncontrollable, natural complications –
including weather forecast planning, machine and software failures, collection and processing
error.
Windy conditions caused the machine to move erratically and work harder to maintain its
calculated course. This caused the battery life to diminish quicker than in normal conditions.
Low battery conditions can lead to “fly-away.” This error is one where the machine’s
programming erroneously searches out its last known landing position, and if it is not in a close
location (because of human error in shortsighted planning), then the machine will search for that
initial take-off position until it drops out of the sky. This situation is funny to think about in
hindsight, but when the predicament occurs and the RPIC realizes that the last ‘Home’ base is 40
miles away in the next city it becomes a serious problem. These cases are prevalent in corridor
surveys where miles of straight-line collections are made. Wind also caused tilt in the machine.
This resulted in the gimbal to over-compensate to capture a flat photograph. While the machine
is calibrated to compensate for this error, the RPIC must maintain the calibration manually. By

52

this human error is introduced. Likewise, during overly gusty conditions, the gimbal often cannot
compensate quickly enough to capture a nadir photograph.
Machine failure can complicate the data collection process when utilizing the UAS drone.
The Phantom 4 requires regular updates to its software and firmware. Failure to do so can lead to
non-flight, crashes, fly-away, non-collection, and miss-collection. DJI recommends updating
machine and software fixes available for the RPIC to prevent or correct known issues (DJI,
2017).
Ground Control Points were placed specifically in logical positions and used to “tie-
down” the area’s XYZ. Errors in GCP surveys typically include input of incorrect datum
systems. State Plane systems can include similar datum projections that can produce results that
can be missed in the processing segment. For example, while ArcGIS is an excellent software to
integrate various coordinate systems it cannot compensate for the observed four-foot vertical
error that accrues processing in State Plane Ohio South HARN. Whilst the GCPs were recorded
in State Plane Ohio South NAD 83, an incorrect categorization of projection would have yielded
erroneous positions. Error produced while processing in Pix4D include misnaming GCPs and
choosing the wrong GCP representation in the GCP/MTP Monitor. Typically, Pix4D
compensated for this error, but made difficult efforts in ground-truthing.
5.3. Future Improvements
Future improvements include suggestions in machine and software, and technique
updates. The technology that powers the machines will continue to improve. In the process of
collecting diversified data, more expensive equipment is a requirement. Octocopters (eight rotor

53

machines) are more stable than the quadcopter used in this research. Additionally, higher
resolution cameras produce more detailed images and better end-results.
Another advancement that can impact future improvements are the use of underground
magnetic location, used for locating underground metallic structures such as abandoned well
locations. One such device is the Fluxgate Magnetometer described in detail by Douglas G.
Macharet, et al. 2016 and used to search for ferromagnetic materials underground. The need for
UAS drones is evident by the parameters required for this sensing technique to perform accurate
data collection. It needs: (1) Precise North Oriented Coverage; (2) Point Separation Flight
Planning; (3) AGL Control; (4) Hover (Macharet, Douglas. et al., 2016).
Successful testing of underground locating of ferrous materials for mining purposes
translates into the availability of the same technology as a crossover into the energy industry in
the form of aerial locating of abandoned locations, and creating the possibility of modifying the
receiver to focus signal reception based on sound wave detection that is particular to unground
`considerations. These sensors can be used to detect anomalies that exceed set ranges, and are
safer for personnel by keeping them at acceptable distances from problem areas. These
technologies presently exist, are growing, and will continue to grow into normal techniques for
use in the energy sector. Finally, the possibility of writing python script that is able to extrapolate
random samples from two or more LAS datasets and create statistical output based on given
parameters will aid in the assimilation of random samples in LAS testing.
What should be said about drones? Is the current preoccupation with them because they
are a cool toy? They are, indeed. But they are more than just a plaything atop a child’s shelf left

54

to collect dust after the luster has gone. They are a tool that has now and in the future helped
mold an industry to become more profitable economically and ergonomically. The tool is able to
work in the energy industry by being able to provide safety to field personnel by allowing
surveys of a wider area with precision and accurate data returns.

55

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Appendix A Tables and Maps
Table 1 GCP report for error accuracy
Mean (ft) 0.000000 0.000000 0.000000
Sigma (ft) 1.245790 1.632082 1.903370
RMS Error
(ft)
1.245790 1.632082 1.903370

Table 2 GCP comparison chart
OID Y X Z DESCRIPTION LOCATION
2 747715.55 2331115.96 1178.65 TARGET DICKINSON
3 748059.06 2330924.42 1154.17 TARGET DICKINSON
101 705680.958 2318898.293 1227.434 TARGET TALLGRASS
104 705093.26 2319151.93 1231.191 TARGET TALLGRASS
203 754124.29 2360173.614 1226.729 TARGET ASPHALT
207 754451.195 2359674.005 1228.093 TARGET ASPHALT

Table 3 Inverse report derived from Trimble Office.
From To
Geodetic
Azimuth
Ellipsoid
Distance
Grid
Azimuth
Grid
Distance
(US survey
foot)
Ground
Distance (US
survey foot)
Elevation
(US
survey
foot)
207 1007022 69°06'14" 0.552 69°06'14" 0.552 0.552 0.004
207 622296 332°00'37" 0.612 332°00'37" 0.612 0.612 0.064
207 517380 43°29'52" 1.43 43°29'52" 1.43 1.43 0.977
207 1007122 204°03'05" 0.459 204°03'05" 0.459 0.459 0.012
207 517302 232°53'25" 4.971 232°53'25" 4.971 4.971 0.727
207 518614 348°10'10" 9.175 348°10'10" 9.175 9.175 1.007

62

Table 4 LiDAR report char
PNT
RCRD
INTENSITY NO
RTRNS
CLASS
CODE
X Y Z GPS TIME LAS REF
323663 157 1 2 2331118.5 747713.38 1179.2 60814.988 s2330745
322767 173 1 2 2331111.3 747722.5 1178.77 60814.956 s2330745
323664 171 1 2 2331109.9 747714.34 1180.2 60814.988 s2330745
296348 61 1 2 2330926.2 748061.54 1149.19 60813.683 s2330745
296347 144 1 2 2330917.8 748062.37 1149.71 60813.716 s2330745
297177 80 1 2 2330924.9 748052.85 1150.5 60813.716 s2330745
517380 158 1 2 2359675 754452.23 1229.07 343955.14 s2355750
517302 204 1 2 2359670 754448.2 1228.82 343955.13 s2355750
518614 82 1 2 2359672.1 754460.18 1229.1 343955.18 s2355750
150418 128 1 2 2360174.4 754121.62 1226.14 341947.31 s2355750
149344 180 1 2 2360177.9 754130.16 1226.17 341947.28 s2355750
149343 195 1 2 2360170.2 754131.67 1226.65 341947.28 s2355750
652271 207 1 2 2319150.1 705097.4 1229.95 236034.27 s2315705
652272 180 1 2 2319160.1 705095.19 1230.15 236034.27 s2315705
651957 189 1 2 2319148.4 705101.44 1230.2 236034.25 s2315705
628767 212 1 2 2318899.7 705682.33 1219.49 236032.13 s2315705
628766 209 1 2 2318891.1 705684.5 1220.63 236032.13 s2315705
629042 183 1 2 2318900 705675.2 1220.54 236032.16 s2315705

Table 5 Absolute camera and deviation uncertainties

X (ft) Y (ft) Z (ft) Omega (degree) Phi (degree) Kappa (degree)
Mean 0.23 0.22 0.48 0.043 0.052 0.015
Sigma 0.06 0.06 0.14 0.006 0.014 0.006

63

Table 6 Relative geolocation variance report
Relative Geolocation Error Images X [%] Images Y [%] Images Z [%]
[-1.00, 1.00] 99.38 100.00 99.07
[-2.00, 2.00] 100.00 100.00 100.00
[-3.00, 3.00] 100.00 100.00 100.00
Mean of Geolocation Accuracy (ft) 5.00 5.00 10.00
Sigma of Geolocation Accuracy (ft) 0.00 0.00 0.00
Geolocation Orientational Variance RMS [degree]
Omega 0.96
Phi 0.58
Kappa 5.27

Table 7 Asphalt random samples
OID Y X Z DESCRIPTION
208 754285.301 2359710.95 1230.703 TARGET
1544815 754285.376 2359710.805 1230.405 LAS
1206500 754285.264 2359711.104 1230.72 LAS
805391 754284.911 2359710.797 1230.61 LAS
496606 754285.87 2359709.06 1232.92 LIDAR

Z Mean: 1230.578333

Z SD: 0.086666667

64

Table 8 Dickinson random samples
OID Y X Z DESCRIPTION
3 748059.064 2330924.416 1154.171 TARGET
483030 748058.894 2330923.95 1154.181 LAS
94555 748059.542 2330924.655 1154.106 LAS
32067 748058.792 2330925.213 1154.163 LAS
296348 748061.53 2330926.07 1149.19 LIDAR

Z Mean: 1154.15

Z SD: 0.022

Table 9 Tallgrass Random Samples (A)
OID Y X Z DESCRIPTION
109 705265.124 2318852.466 1225.284 TARGET
3326 705265.754 2318853.633 1225.154 LAS
980 705258.406 2318853.791 1225.08 LAS

Z Mean: 1225.172667

Z SD: 0.055666667

65

Table 10Tallgrass Random Samples (B)
OID Y X Z DESCRIPTION
106 2318991.437 704757.168 1228.376 TARGET
10362 704756.878 2318994.019 1228.627 LAS
5521 704762.027 2318987.276 1228.32 LAS

Z Mean: 1228.441

Z SD: 0.093

Table 11 Deviation report
POINT RECORD Y X Z PARENT LOCATION A Sample
150419 754123.146 2360166.87 1226.33 s2360750
844333 754123.949 2360165.654 1226.517 Asphalt Results Tracks 2
817224 754122.973 2360168.931 1226.495 Asphalt Results Tracks 2
150435 754120.303 2360165.437 1226.56 s2360750

Average of the samples 1226.4755

Average deviation of the samples 0.07275
POINT RECORD Y X Z PARENT LOCATION B Sample
61994 747760.881 2330755.766 1212.1 s2330745
701060 747760.291 2330753.544 1212.553 Dickinson Results Tracks 2
701164 747763.225 2330753.822 1212.487 Dickinson Results Tracks 2
701252 747763.225 2330758.613 1212.067 Dickinson Results Tracks 2

Average of the samples 1212.30175

Average deviation of the samples 0.21825

66

Table 12 Root Mean Square/Altitude relationship table (Source: ASPRS 2015)

Altitude (m) Positional RMSEr (cm) Altitude (m) Positional RMSEr (cm)
500 13.1 3000 41.6
1000 17.5 3500 48
1500 23 4000 54.5
2000 29 4500 61.1
2500 35.2 5000 67.6

Table 13 USGS check shot point:
Job: ASPH_GCP Version:12.50 Units: US Survey Feet Elevation Description
FREO 804303.239 2315483.787 1011.685 VRS CORS Station
21 754323.051 2366807.185 1295.349 USGS MONUMENT E-64
22 754323.089 2366807.154 1295.378 USGS MONUMENT E-64

67

Table 14 LAS points derived from UAS:
POINT_RECORD X Y Z LOCATION
247183 2319152.886 705093.397 1231.15 TALLGRASS
242670 2319151.215 705092.345 1231.31 TALLGRASS
147362 2319151.28 705093.679 1231.239 TALLGRASS
91755 2318898.821 705679.948 1227.51 TALLGRASS
86905 2318896.981 705680.937 1227.501 TALLGRASS
80333 2318899.043 705682.934 1227.163 TALLGRASS
442028 2331115.893 747715.521 1177.104 DICKINSON
441971 2331116.207 747715.697 1178.246 DICKINSON
445941 2331116.096 747715.444 1178.482 DICKINSON
477674 2330924.348 748059.049 1154.134 DICKINSON
94555 2330924.655 748059.542 1154.106 DICKINSON
32067 2330925.21 748058.792 1154.163 DICKINSON
1007122 2359673.818 754450.776 1228.105 ASPHALT
622296 2359673.718 754451.735 1228.157 ASPHALT
1007022 2359674.521 754451.392 1228.097 ASPHALT
1681069 2360173.719 754124.315 1226.497 ASPHALT
1665724 2360173.084 754124.041 1226.742 ASPHALT
1278052 2360173.372 754124.781 1226.682 ASPHALT

68

Table 15 Data Sources
REQUIRED DATA LOCATION SOURCE STATUS
Images for Asphalt Plant 40.062264° -81.101547° UAS Collected and
processed
Images for Dickinson Stock Lake 40.046282° -81.204402° UAS Collected and
processed
GCP for Compressor Site placed throughout project Trimble
GPS
Collected and
processed
GCP for Asphalt Plant placed throughout project Trimble
GPS
Collected and
processed
GCP for Dickinson Stock Lake placed throughout project Trimble
GPS
Collected and
processed
LiDAR from OGRIP (Ohio
Graphically Referenced
Information Program)
Tile(s) S2315705 and
S2315700
OGRIP For Comp Plant
LiDAR from OGRIP (Ohio
Graphically Referenced
Information Program)
Tile(s) S2360750 and
S2355750
OGRIP For Asphalt Plant
LiDAR from OGRIP (Ohio
Graphically Referenced
Information Program)
Tile(s) s2330745 OGRIP For Lake
GPS As Built and Topo data from
CAD
NAD 83 Ohio North State
Plane
Field
Collection
CAD File - Collected
and Processed
DEM from OGRIP - 1:24000 Tiles Bethesda CA332 OGRIP For Asphalt Plant
DEM from OGRIP - 1:24000 Tiles Quaker City CK106 OGRIP For Comp Plant
CAD file to process data PC - AutoCAD Civil 3D

File
GIS file to correlate data PC - ArcGIS 10.4.1

File

69

Figure 6 Asphalt site volume map.

70

Figure 7 Asphalt site contour map – P 1

71

Figure 8 Asphalt site contour map – P 2

72

Figure 9 Asphalt site contour map P 3

73

Figure 10 As-Built compilation report Price Pad P 1

74

Figure 11 As-Built compilation report Price Pad P 2

75

Figure 12 grass site As-built/UAS comparison map

76

Figure 13 LiDAR/LAS comparison Chart 1

77

Figure 14 LiDAR/LAS comparison Chart 2

Abstract (if available)

Abstract This study detailed the data collection, processing, and source comparison of DJI Unmanned Aerial System (UAS) drone data from different examples of topographical datasets for accuracy testing. Three datasets were chosen as they were characteristically different, these terrains were those typically encountered while surveying in the energy industry and are representative of terrain types encountered in the south Ohio area. More broadly they are comparable with other terrain systems. ❧ The system used to collect the UAS data consisted of a DJI Phantom 4 unmanned aerial vehicle controlled by DJI Ground Station Pro on an iPad Pro that input and monitored flight parameters. The processing used various software applications. These included Pix4D, which was the photogrammetry software used to convert the data into georeferenced mosaics, models, and point clouds. Additionally, Esri’s ArcGIS and Idrisi Terrset were also used in performing analysis. ❧ The data was then analyzed to find correlation to LiDAR and ground control to compare elevation similarities. For the purpose of this study ground control points and LiDAR are considered the trusted source of reference accuracy and precision. Accuracy was assessed against the control material by inversion methods, geometry, and visual assessments. The testing concluded cohesive data precision, accuracy, and detailed the process of creating remotely-sensed materials and their conversion to geometrically accurate data.

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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Jurden, Charles Ray, Jr. (author)

Core Title Utilizing advanced spatial collection and monitoring technologies: surveying topographical datasets with unmanned aerial systems

School College of Letters, Arts and Sciences

Degree Master of Science

Degree Program Geographic Information Science and Technology

Publication Date 04/12/2018

Defense Date 03/16/2018

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag accuracy,ArcGIS,AutoCAD, Terrset,data,data collection,DJI Unmanned Aerial System,drone,Esri,OAI-PMH Harvest,processing,source comparison,topographical,UAS

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Fleming, Steven (committee chair), Marx, Andrew (committee member), Wilson, John (committee member)

Creator Email charlesjurden@me.com,jurden@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-9138

Unique identifier UC11672288

Identifier etd-JurdenChar-6236.pdf (filename),usctheses-c89-9138 (legacy record id)

Legacy Identifier etd-JurdenChar-6236.pdf

Dmrecord 9138

Document Type Thesis

Rights Jurden, Charles Ray, Jr.

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA