Changes between Version 10 and Version 11 of Procedures/PhotoScan


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Timestamp:
Nov 8, 2018 2:27:47 PM (5 months ago)
Author:
wja
Comment:

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  • Procedures/PhotoScan

    v10 v11  
    3535}}}
    3636
    37 * If no GCPs have been input in config file,  (gcp_csv_path = None) '''or if gcp_csv_path does not exist''', then ps_ortho_processing_before_input_gcp.py will run through the whole PhotoScan workflow without GCPs.
     37* If no GCPs have been input in config file,  (gcp_csv_path = None) or if gcp_csv_path does not exist, then ps_ortho_processing_before_input_gcp.py will run through the whole PhotoScan workflow without GCPs.
    3838* If a path to GCP CSV has been input into the config file, these GCP coordinates will need to be manually positioned to their correct locations on the aligned photographs. Once this has been achieved, the second script can be run:
    3939
     
    4545The same config template is used.[[BR]]
    4646The project directory (defined in config file) is the location of the PhotoScan project file (*.psx) and other data produced whilst processing.[[BR]]
    47 The output directory (also defined in config) is where the Point Cloud, DEM and/or Orthomosaic is exported, if the associated parameters are True in config file. If the output directory does not exist, then it will be created.
     47The output directory (also defined in config) is where the Point Cloud, DEM and/or Orthomosaic is exported, if the associated parameters are True in config file. If the output directory does not exist, then it will be created.[[BR]]
     48[[BR]]
     49'''Quality Checks'''[[BR]]
     50To assess the quality of the exported data, compare the orthomosaic to Fenix/Owl data, or any higher spatial resolution imagery that you have access to. Use this to assess if the X and Y accuracy is suitable.[[BR]]
     51For the Z (vertical) accuracy, you should compare the generated DEM to any points of known elevation at the time of flight but not the GCPs used in processing. For UK projects, there is good coverage of LiDAR data which may be able to make a good comparison. You can calculate the bias and RMSE between the processed elevations and the expected elevations (inferred from proxy data). Any statistical metrics calculated should be reported in the delivery's Read_Me.[[BR]]
     52If the accuracy of the data is questionable, investigate whether this is caused by the following:
     53 * GCPs
     54  * GCPs need to be frequent, well spread, precise and in the correct units. Also consider reprojection errors if the GCPs and/or exported data are in contrasting projections.
     55 * Eventfile
     56  * Check the values in the eventfile. There may have been a problem when extracted them from the navigation data.
     57 * Processing
     58  * Check that the GCP placement in PhotoScan has been undertaken in as many photographs that GCPs are present in as possible. Also look at the residual error of the projects spatial fit. Unusually high error values for a particular GCP marker would suggest that it has been placed in the wrong location.
    4859
    4960== Creating Delivery ==