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+---
+title: "Analysis of UAS data processing results"
+subtitle: "Center for Geospatial Analytics at North Carolina State University"
+author: "Justyna Jeziorska, Helena Mitasova & Corey White"
+format:
+ revealjs:
+ theme: [simple, ../../../../theme.scss]
+---
+
+
+
Objectives
+
+
Understand how to interpret a processing report
+
Compare errors and survey data from different flights
+
Recognize differences in geoprocessing products generated by different software
+
Understand significance of using GCPs in the processing and their impact on the final products
+
Recognize what processing steps need to be modified in order to improve particular errors
+
+
+
+
Objectives
+
+
Understand what causes the 'Bowl effect' and know the solutions to fix it
+
Execute simple terrain measurements in Agisoft Photoscan
+
+
+
+
+
Flights Oct. 6th 2015
+
+
+
+
+
Flight Feb. 6th 2018
+
+
+
+
+
Flights Oct. 6th 2015
+
+
+
+
+### Analyzing the processing report
+
+::: {.columns}
+:::{.column width="40%"}
+
+Includes:
+
+- Orthophoto and digital elevation model sketch;
+- Camera parameters and survey scheme
+- Tie points data export (matching points and panoramas)
+- Image overlap statistics
+- Camera positioning error estimates
+- Ground control point error estimates
+:::
+
+:::{.column width="50%"}
+
+:::
+:::
+
+
+
+
Orthophoto
+
+
+
+
Survey data
+
+
+
+
Flight plans
+
+
+
+
Flight plan – flight 1
+
+
+
+
Flight plan – flight 2
+
+
+
+
Ground Control Points
+
+
+
+
Ground Control Points
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
Camera calibration report
+
+
+
+
+### Analyzing the processing report
+
+::: {.columns}
+:::{.column width="40%"}
+
+Includes:
+
+- While carrying out photo alignment PhotoScan estimates both internal and external camera orientation parameters, including nonlinear radial distortions.
+
+- Tools > Camera calibration
+:::
+
+:::{.column width="50%"}
+
+:::
+:::
+
+
+
+
Image residuals
+
+
+
+
Image residuals
+
+
+
+
Image residuals
+
+
+
+
+
Image residuals
+
The geometric error corresponding to the average image distance, measured in pixels, between:
+
+
+
+
+
Image residuals
+
This reprojection error is equivalent to the root mean square (RMS) image residuals used in photogrammetric literature
+
+
+
+
+
Flight path
+
+
+
+
Flight path in 3D
+
+
+
+
Digital Surface Model
+
+
+
+
Digital Surface Model
+
+
+
+
+
DSMs comparison
+
+
difference [m] between DSMs generated
+based on data from two consecutive flights
+
+
+
+
+
DSMs comparison by software
+
+
+
+
+
DSMs comparison -GCPs
+
+
+
+
+
'Bowl effect'
+
effect can be introduced during photo alignment, in case camera calibration estimates are inaccurate
+
+
+
+
+
'Bowl effect'
+
effect can be introduced during photo alignment, in case camera calibration estimates are inaccurate
+
+
+
+
+
+
'Bowl effect'- solutions to the problem
+
+
If camera calibration is known in advance- it can be loaded in PhotoScan and fixed during photo alignment
+
Optimization procedure - recommended approach
+
+
based on camera or GCP coordinates
+
performed after photo alignment
+
is recommended to perform optimization based on ground control data in any case, even if precalibrated cameras are used
+
+
+
+
+
+
Optimization
+
+
+
+
+
What is an optimization?
+
+
PhotoScan performs full photogrammetric adjustment taking into account additional constraints introduced by ground control data
+
Extrinsic and intrinsic parameters for all cameras are optimized at this step, in contrast to the simple 7-parameter transform used for georeferencing by default
+
Optimization helps to significantly improve accuracy of the final solution
Center for Geospatial Analytics at North Carolina State University
+
+
+
+
+Justyna Jeziorska, Helena Mitasova & Corey White
+
+
+
+
+
+
+
+
+
+Objectives
+
+
+
+Understand how to interpret a processing report
+
+
+Compare errors and survey data from different flights
+
+
+Recognize differences in geoprocessing products generated by different software
+
+
+Understand significance of using GCPs in the processing and their impact on the final products
+
+
+Recognize what processing steps need to be modified in order to improve particular errors
+
+
+
+
+Objectives
+
+
+
+Understand what causes the ‘Bowl effect’ and know the solutions to fix it
+
+
+Execute simple terrain measurements in Agisoft Photoscan
+
+
+
+
+
+Flights Oct. 6th 2015
+
+
+
+
+
+Flight Feb. 6th 2018
+
+
+
+
+
+Flights Oct. 6th 2015
+
+
+
+
+
Analyzing the processing report
+
+
+
Includes:
+
+
Orthophoto and digital elevation model sketch;
+
Camera parameters and survey scheme
+
Tie points data export (matching points and panoramas)
+
Image overlap statistics
+
Camera positioning error estimates
+
Ground control point error estimates
+
+
+
+
+
+
+
+Orthophoto
+
+
+
+
+
+Survey data
+
+
+
+
+
+Flight plans
+
+
+
+
+
+Flight plan – flight 1
+
+
+
+
+
+Flight plan – flight 2
+
+
+
+
+
+Ground Control Points
+
+
+
+
+
+Ground Control Points
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
+Camera calibration report
+
+
+
+
+
Analyzing the processing report
+
+
+
Includes:
+
+
While carrying out photo alignment PhotoScan estimates both internal and external camera orientation parameters, including nonlinear radial distortions.
+
Tools > Camera calibration
+
+
+
+
+
+
+
+Image residuals
+
+
+
+
+
+Image residuals
+
+
+
+
+
+Image residuals
+
+
+
+
+
+Image residuals
+
+
+The geometric error corresponding to the average image distance, measured in pixels, between:
+
+
+
+
+
+Image residuals
+
+
+This reprojection error is equivalent to the root mean square (RMS) image residuals used in photogrammetric literature
+
+
+
+
+
+Flight path
+
+
+
+
+
+Flight path in 3D
+
+
+
+
+
+Digital Surface Model
+
+
+
+
+
+Digital Surface Model
+
+
+
+
+
+DSMs comparison
+
+
+
+difference [m] between DSMs generated based on data from two consecutive flights
+
+
+
+
+DSMs comparison by software
+
+
+
+
+
+DSMs comparison -GCPs
+
+
+
+
+
+‘Bowl effect’
+
+
+effect can be introduced during photo alignment, in case camera calibration estimates are inaccurate
+
+
+
+
+
+‘Bowl effect’
+
+
+effect can be introduced during photo alignment, in case camera calibration estimates are inaccurate
+
+
+
+
+
+‘Bowl effect’- solutions to the problem
+
+
+
+If camera calibration is known in advance- it can be loaded in PhotoScan and fixed during photo alignment
+
+
+Optimization procedure - recommended approach
+
+
+based on camera or GCP coordinates
+
+
+performed after photo alignment
+
+
+is recommended to perform optimization based on ground control data in any case, even if precalibrated cameras are used
+
+
+
</ol>
+
+
+
+Optimization
+
+
+
+
+
+What is an optimization?
+
+
+
+PhotoScan performs full photogrammetric adjustment taking into account additional constraints introduced by ground control data
+
+
+Extrinsic and intrinsic parameters for all cameras are optimized at this step, in contrast to the simple 7-parameter transform used for georeferencing by default
+
+
+Optimization helps to significantly improve accuracy of the final solution
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 
+
+
+ 
+
+
+
+
+ 
+
+ 
+
+ 
+
