Changes between Version 5 and Version 6 of Sensors/LeicaLIDAR/FWMarksNotes

Jan 26, 2010 11:02:30 AM (9 years ago)



  • Sensors/LeicaLIDAR/FWMarksNotes

    v5 v6  
    2626 * No changes to the calibration flights except to collect FW data. Only change to the processing is to find the timing offset between FW and discrete points.
    2727 * Pre-trigger - like a buffer zone to record digitised samples before the first return. Default is 5m.
     28 * Waveform and discrete data use different scalers for the intensity values and so will result in different intensities.
    3030== Software ==
    4444  * ALS system refers to a virtual rotation axis (assumes a PAV80 stabilised mount even if you do not have one)
    4545  * we need to update GPS lever arms in FCMS v3.15.
    46   * .SUP file will automatically offset to the mirror centre in ALSPP processing
     46  * .SUP file will automatically offset to the mirror centre in ALSPP processing (Need IPAS version 1.35 for this)
    4747  * Unsure as to whether leverarms need to be updated in IPAS or not - also how do we know IMU offsets to apply?
    5252 * To process full waveform data in ALSPP - Select "process waveform data" from the inputs menu and tick the box. Enter the "Trigger Delay" - this is the time offset between discrete and waveform data.
    5353 * ALSPP looks for the "RawWfd" folder - this may imply that renaming the directory structure could cause problems.
     54 * ALSPP can limit the number of points it puts in a LAS file. This allows long flight lines to be split up into more manageable files.
     55 * Trigger delay needs to be derived - hopefully it remains constant throughout each flight line and whole flying season - this needs to be checked and monitored. Temperature may also affect it.
     56  * Will have 2 values - one for 4ns pulse width ("over TPR") and one for 9ns pulse width ("under TPR")
     57  * Use waveviewer tool with lines at 4ns to get the 4ns offset, and lines at 9ns to get the 9ns offset
     58  * Use points throughout flight line not just at start to derive the offset.
     59  * Procedure
     60   * In waveviewer "Ret point loc" is the discrete return time (from emit to receive) for the first return
     61   * intensity is the value for each discrete return