Changes between Version 10 and Version 11 of Procedures/AlsprocProcessing

Sep 2, 2014 10:09:46 AM (5 years ago)



  • Procedures/AlsprocProcessing

    v10 v11  
    11== Overview ==
    3 The workflow of alsproc, modelled after the hyperspectral processing software APL, generally works as such:
     3This guide describes how to process LiDAR data using alsproc and the ALS Post Processor
    5 [[Image(workflow_diagram.png)]]
    7 As the processor you will use ''generate_alsproc_config'' to create a configuration file, edit this with a text editor to fill in any parameters specific or special to your flight, then instruct alsproc to perform the operations described in the .cfg file. You'll need to validate your data before you proceed onto any other steps, and address any issues with the processed data by making further changes to the configuration file or notifying the maintainer or calibrator of any issues upstream.
     5Alsproc can either be run locally using (linked as just alsproc) or on the grid using Note that presently it will only run correctly on fedora 19 machines and as such you must submit to the development grid. Check with someone on how to do this, you'll need to update SGE_CELL.
    97== Configure ==
    108The configuration file is made with the program. It will examine your current working directory and derive a project directory, from which it will determine the best available calibration to base your configuration file on, and populate it with information derived from your flightlines. This can take a while, as it needs to perform a cursory check on all of the raw data.
     10This presently only works on fedora 19 machines.
    3838Flightlines which alsproc thinks it might not be able to process based on this check will be flagged here, as in the case of the last flightline, and not be marked to be processed.
    40 Next, edit the .cfg file created as a result. If you did not specify, it will be under processing/als50/.
     40Next, edit the .cfg file created. If you did not specify, it will be under processing/als50/*.cfg.
    4242Fields of particular interest to you as a data processor are:
    5959|| ascii || experimental/analytical reasons || txt || .txt ||
     61It is likely that there will be a pitch/roll offset as described below. Correcting this works in a similar manner to hyperspectral SCT correction. You will need to add the following fields to the cfg file to iterate over a range of pitch/roll/heading corrections:
     64#roll-correct = -0.0035000
     65roll-start = -0.0030000
     66roll-end = -0.0040000
     67roll-inc = -0.0001
     70This would result in 11 las files being created, each at a 0.0001 increment. Switch out roll for pitch or heading if you need to process those. You need to comment out or remove the -correct value or alsproc will not run.
     72Note that you can only run one of pitch/roll/heading as incrementing at present, this is to stop confusing files but could be added in if it is felt it is needed.
     74[[Be certain about your -inc value as this can result in very large numbers of files being produced.]]
    6176You will then see a section for each flightline. process_line should be set to true for each flightline unless there was some problem, in which case the maintainer for alsproc should be contacted.
    7489multi-pulse = false
    7892== Generate ==