== Airborne Laser Scanner (ALS) processing  ==

General Processing with a settings (.reg) file
 1. Start ALS PP (possibly using [wiki:Processing/LidarWining Linux])
 1. Load in the reg file to set the specific settings for the project.
   * Reg files under ~arsf/calibration/lidar. Usually, pick the calibration that's the most recent prior to your project day. However, sometimes calibration flights are flown AFTER data is collected. Check with someone if unsure.
   * File > Load Settings
 1. For Wine, Go to Inputs > Range Correction and for Intensity Based Range Correction browse to \users\rsg\arsf\calibration\lidar\... and select the relevant SN089_IBRC*txt file for the flight day you are processing
 1. Set the Goto Folder to the main project directory
   * File > Set Goto Folder
 1. Check the settings are appropriate for the project before proceeding (see below). This is important if using a reg file for a different project.
 1. Select POS filename
   * Click Browse and add the .sol file (posatt/ipas_honeywell/proc/)
 1. Select the Output directory
   * Click Select > Goto Folder and select <projname>/processing/als50/las. You should create directory if it doesn't exist.
 1. If the project is not in the UK, you will need to change the projection (File -> Output Options -> Change output format), change: zone, height and width 
 1. Save settings for future re-processing purposes.
   * File > Save Settings (e.g. aux_files/2009280b.reg)
 1. Add the raw SCN data
   * Click Add and browse to the parent raw data directory.  This will add all flight lines in the immediate child directories. liar->als50->RawLaser
 1. Run the processing
   * Run > Run

== Setup of the system ==

 * Hardware options. Once set these should never change (unless the system is modified etc) Should be supplied when the system is delivered. Can view/set these from File > Processing Options.
 * Output file options. Set the projection details (usually OSGB36), LAS file format, and whether want GeoTIFF or ASCII output awswell. Also contains options for debugging.

 * Input options
   * Atmospheric Correction.  Need values of the altitude, temperature and pressure for a low altitude and high altitude. With these values a correction gradient will be produced.
   * Range Correction. A time-distance delay in metres of the ALS system, in the measurement of range data. (This is complicated...see user manual for details)
   * Scanner Correction. These do not need to be changed after the calibration/boresighting of the system.
   * POS errors. Angular difference between the IMU and the ALS optics reference frames. Needs to be known accurately.
   * Elevation offset. This needs to be set if we have ground control points: is normally non-zero.  It is identified using the TScan Control Report (eh?). The LIDAR is then reprocessed using the opposite of the DZ offset.
   * Intensity.  Use the Raw intensity.

== Possible errors ==

 * ALSPP.EXE on Linux
   
   1. If a Windows crash message appears when trying to 'Run', ensure the POS file is pointed to on the Linux filesystem and not the Windows hard drives (D:,.. etc.).