Changes between Version 3 and Version 4 of Sensors/LeicaLIDAR/FWMarksNotes


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Timestamp:
Jan 26, 2010 10:42:47 AM (10 years ago)
Author:
mark1
Comment:

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  • Sensors/LeicaLIDAR/FWMarksNotes

    v3 v4  
    33== Concepts and Hardware ==
    44
    5  * Discrete point recording remains unchanged - full waveform digitiser is an extra. Nothing has changed for the AGC/mainboard of the ALS so the raw laser .SCN files will be the same as before. Extra files will be created that contain the waveform data.
     5 * Discrete point recording remains unchanged - full waveform digitiser is an extra.
     6  * Nothing has changed for the AGC/mainboard of the ALS so the raw laser .SCN files will be the same as before.
     7  * Extra files will be created that contain the waveform data. Waveform files (.LWV) will be in the raw_wfd directory, SCN files in the raw_laser directory.
     8  * Waveform files have A or B in filename depending on which data board (A or B) acquired it. When processing both files are taken together.
    69 * The digitiser starts recording from the first returned peak for the number of required samples (256/128 @ 1ns or 256/128/64 @ 2ns)
    710  * If first return is noise (cloud/seagull) then the digitiser will start recording there and not at the target.
     
    2124 * Maximum rate of acquiring digitised full waveform data is 120KHz. If a higher rate is used then the waveform data will record for every other emitted pulse. But the SCN files will still be recorded at the high rate.
    2225 * Pulse length (sampling rate) should be chosen based on the maximum height of targets in the area. E.G. if all low lying targets then there is no point using 256 samples at 1 ns - better to use 128 at 1 ns.
    23 
     26 * 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.
    2427
    2528== Software ==
    2629
    27  * ALSPP outputs in LAS 1.3 format
     30 * ALSPP outputs in LAS 1.3 format which supports full waveform data (and also LAS 1.0)
     31 * ALSPP takes 10 times as long to process the data to produce a LAS file when using FWD
    2832 * Includes a simple waveform viewer
    2933  * Displays waveform and discrete points
    30   * There is a "constant" timing offset between the waveform and discrete points - thought to be due to processing time
     34  * There is a "constant" timing offset between the waveform and discrete points - thought to be due to processing time. This should be removed at calibration
     35
     36 * New version of Terrascan capable of displaying full waveform data and "creating extra" points from the waveform
     37
     38
     39== Something ==
     40
     41 * When processing data collected after using FCMS v3.15 (anything after Jan 2010 ?)
     42  * ALS system refers to a virtual rotation axis (assumes a PAV80 stabilised mount even if you do not have one)
     43  * we need to update GPS lever arms in FCMS v3.15.
     44  * .SUP file will automatically offset to the mirror centre in ALSPP processing
     45  * Unsure as to whether leverarms need to be updated in IPAS or not - also how do we know IMU offsets to apply?