Presentation by Renee Walmsley, Remote Sensing Program Manager at Tetra Tech, for the August 16, 2017 Rocky Mountain UAS Professionals Meetup at the Esri Broomfield office.

1. Rocky Mountain UAS
Professionals
16 August 2017
Unmanned Aerial Systems for Precision Mapping
Tetra Tech Geomatic Technologies Group

2. Just the facts
• Founded in 1966
• $2.6 billion annual revenue in
FY2016
• 16,000 employees worldwide
• A network of approximately 400
offices
• Worked on 60,000 projects in more
than 100 countries in FY2016
• Publicly traded on NASDAQ
as TTEK
2CompanyOverview

3. Geomatic Technologies Focus Areas
3
 Photogrammetric Mapping
 Digital Orthoimagery
 Airborne Light Detecting and Ranging (LiDAR)
 Multi & Hyperspectral Technology
 Satellite Imagery Collection & Analysis
 Geographic Information Systems (GIS)
 Data Management & Visualization
 Web Mapping Applications
 Historical Aerial Photography
 Oblique Imagery
 Thermal Imagery
 Magnetometry
 Unmanned Aerial Surveys (UAS)
 Mobile and Terrestrial LiDAR

4. Capabilities: Precision Mapping and Imagery Tools
Current and Historical Aerial
Photography
– provides information about land use
and change detection. CIR imagery
detects stress or vigor of vegetation.
3D Terrain Models & Topographic
Maps
– shows detailed changes in terrain
elevation to support engineering design,
hydrologic modeling, linear routing or
line of site assessments.
LightDetecting& Ranging(LiDAR)
– feature extraction to create as-builts of
existing structures, vegetation and high
resolution terrain mapping.
Hyperspectral Technology
– identify, map and analyze spectrally
unique plant communities, soil types,
and water conditions for baseline &
monitoring.
Airborne ThermalSensing
– thermal infrared imagery overlaying
digital ortho photographs depicts the
distribution of water temperatures.
Airborne Magnetometry
– identify subsurface anomalies such as

5. High Resolution Aerial Imagery
Tetra Tech project Name: Los Medanos / Location: Contra Costa, California

6. Compiled Mass-Points, Breaklines and Planimetry
Tetra Tech project Name: Los Medanos / Location: Contra Costa, California

7. TIN (Triangulated Irregular Network)
Created from Compiled Data
Tetra Tech project Name: Los Medanos / Location: Contra Costa, California

8. Multispectral and Hyperspectral Imagery

9. Introduction to LiDAR

10. LiDAR – High Resolution Terrain Model
First Image:
Highest hit
LiDAR points in
heavily
vegetated
region. LiDAR
point density
collection was
8.9pts/sq.
meter.
Second Image:
Terrain model
with vegetation
points removed
shows ground
detail (terrain
changes, roads,
river banks, etc.

11. Unmanned Aerial Systems (UAS)
 Ideal for Small Area/Sensitive Area Collection
 Faster mobilization to remote areas
 Emergency Response
 Faster product generation
 Time-sensitive projects
 Ability to collect with multiple sensors/ change sensors
in the field
 Cost effective
 Below cloud deck acquisition
 Oblique acquisition

12. UAS Applications
 Oblique Imagery: Capture of cliffs or other coastal features
allows for mapping where manned sensors cannot
 High resolution imagery: less than one centimeter GSD
 Volumetrics: With high relative accuracy, measurements will
be approximately 3 cubic cm without GCPs
 Tide coordinated acquisition: With the ability to fly below
clouds and at night (with a waiver), specific high or low tide
conditions can be captured
 Rapid Response: FAA emergency waivers and UAS flight
flexibility make UAS a great tool
 Thermal imagery to detect wildlife, plant life, etc. in a more
economic and localized way than with manned aircraft

13. Unmanned Aerial Systems
 DJI Phantom and Inspire (Multi-Rotor)
 Very Cheap Consumer Grade ($1350-$3000)
 Sufficient Electronics to Meet FAA Restrictions
 High resolution Video (1080P and photographs)
 Limited georeferenced output with Pix4D
 Semi-Autonomous
 Vertical landing
 SenseFly ebee (fixed wing)
 Longer flight duration time
 Ideal for larger area collection
 GSD of 1.5 cm pixel
 Limited georeferenced output with Pix4D
 Semi-Autonomous
 Beyond line-of-sight
 Requires a larger landing area

14. Unmanned Aerial Systems
 SkyProwler (VTOL)
 Switchblade mechanism allows for
longer/faster flights
 Hover and vertical take off/landing
 Gimbal stabilizationfor camera
 16MP camera with NIR filter
 Cargo drop door
 Beyond line-of-sight and dusk collection

15. UAS Sensors
 Color imagery cameras
 High definition video cameras
 4-band RGBI cameras
 Thermal sensors (FLIR)
 Topographic LiDAR
 Hyperspectral
 Standard frame camera
 Frame based video
camera
 Metric frame camera
 LiDAR
 FLIR

16. Data Collection
 Ground control
 Specialized pre-flight
planning software
 Airspace considerations
 Safety considerations
 License

17. Data Processing
 Orthoimagery
 Digital Surface Model (DSM)
 Digital Elevation Model
(DEM)
 Contours
 Planimetrics
 3-D Point Cloud
 Feature extraction
 Classification

18. Deliverables
 Orthoimagery
 Contours
 Planimetrics
 Classified LiDAR
 Topographic DEM
 Intensity/Reflectance
 NIR Imagery
 Volumetric Calculations
 Slope Calculations
 Change DetectionAnalysis
 Heat DetectionAnalysis
 VegetationAnalysis

19. Project Example: Diablo Canyon Bluff Study
 LiDAR and Aerial Photography of a Seacoast
Bluff near the Diablo Canyon Power Plant on the
Central California Coast
 Comparison of 2010 to 2015 LiDAR and to
several epochs of photogrammetric mapping
 Highlighted areas of greatest change and
presented suggestions for future studies of bluff
erosion
 Change detection analysis

20. Project Example: Quarterly Landfill Mapping
 Aerial Photography of Six Local Landfills
 Developed methods to quickly generate
terrain models for volumetric analysis
 Delivery within one week included terrain
models and contour maps
 Results reviewed by stereo inspection
and accuracy routinely tested by
comparison to landfill and haul records
 Acquisition below fog/cloud cover was
key to meeting schedule deadline

21. Project Example: Pismo Beach Bluff
21

22. Project Example: Bennett Landfill
Considerations:
 Flight Planning
 Ground Control Points
 Accuracy
 Datasets
 Data points are a DSM (surface, not ground)
 Size of Project
 Turn-around Time

23. Project Example: UAV Modeling and Accuracy Evaluation
Vasco Road is close to our office in Lafayette

24. UAV Modeling and Accuracy Evaluation: Vasco Road
Vasco Road is close to our office in
Lafayette so we thought to deploy
our UAV as a test.

25. 800+ Photos were taken
UAV Modeling and Accuracy Evaluation: Vasco Road

26. High Resolution Imageryproduces adetailed DTM
UAV Modeling and Accuracy Evaluation: Vasco Road

27. 0
2
4
6
8
10
12
14
16
18
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
Distribution of Error
mz = -.11’
s = .35’
UAV Modeling and Accuracy Evaluation: Vasco Road
Tested in 72 Locations

28. UAS Lessons Learned
 Value of UAS comes from the data, not the platforms
 Project objectives determine approach
 Even “easy to fly” systems can be challenging
 Not everyone who has a UAS can/should fly
commercially
 Accuracy and mapping requirements are not just
processing
 Ground checkpoints/targets
for accuracy reporting
 FAA Regulations for UAS are set
to aviation industry standards –
practice them, keep our standards high

29. Accuracy Lessons Learned
• Lens Stability, Resolution and Software are Key:
▪ The Sony sensor produced accuracies comparable to manned cameras
▪ UAS lenses are not calibrated and contain instabilities
• Data points are a DSM surface: software can only model
what is visible
• Contours of 2ft can be generated to accepted standards
easily.
• With proper control for checking and measurement the
1ft contours are possible
• Size of the project matters
• Accuracy and mapping requirements must be met by
proper hardware and planning - not just software.

30. Contact Information
Renee Walmsley, PMP, GISP
Remote Sensing Program Manager
Tetra Tech, Inc.
925.584.0049
Renee.Walmsley@tetratech.com