PhotoScan Processing
This page aims to guide a user through photogrammetry processing using Agisoft PhotoScan.
Refer to ~arsf/doc/photoscan_processing/ for a step by step guide using a PhotoScan GUI.

Overview: The following files comprise the arf_photoscan library:

arf_photoscan/
	init.py
	ps_export.py
	ps_processing.py
	ps_tools.py
	ps_tools.pyc
ps_ortho_processing_after_input_gcp.py
ps_ortho_processing_before_input_gcp.py
README.md
templates/
	ps_workflow.cfg

The arf_photoscan library currently contains two scripts for automating PhotoScan processing of NERC-ARF data: ps_ortho_processing_before_input_gcp.py will set up a PhotoScan project and align photographs. If Ground Control Points (GCPs) are available, then the script will stop and prompt you to manually locate them in the PhotoScan project. If no GCPs are available, the script will complete the whole PhotoScan processing workflow without (obviously accuracy of data is significantly reduced). This step is not automated. ps_ortho_processing_after_input_gcp.py is run after the and placement of Ground Control Points.

Ground Control Points
Coordinates of GCPs in CSV format can be added to PhotoScan. The user will then need to 'drag and drop' the marker locations to their locations visible in the photographs input. This needs to be done for all photographs each GCP is visible in.
Note: once a couple of GCPs have been located in multiple respective photographs; the 'reproject' button (looks like a recycling symbol) will automatically place the remaining photo. These will still need to be accurately places, but will save a lot of time nevertheless.

Running a script:

• Update config file (template is located in /templates/ps_workflow.cfg).
• As airborne, in the rsg-photoscan virtual machine, run:

/opt/photoscan/photoscan.sh -r ps_ortho_processing_before_input_gcp.py -c [CONFIG]

• 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.
• 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:

/opt/photoscan/photoscan.sh -r ps_ortho_processing_before_after_gcp.py -c [CONFIG]

Config Information
The same config template is used.
The project directory (defined in config file) is the location of the PhotoScan project file (*.psx) and other data produced whilst processing.
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.