Changes between Version 26 and Version 27 of Sensors/LeicaLIDAR/MikesNotes


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Timestamp:
Sep 5, 2008 4:06:29 PM (10 years ago)
Author:
mggr
Comment:

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  • Sensors/LeicaLIDAR/MikesNotes

    v26 v27  
    1111 * problem uploads to go to incoming/ dir
    1212
    13 
    14 
    15 == Mission planning considerations ==
    16 
    17 Water absorbs IR, so expect poor returns from wet surfaces.  Ideally one should wait for a whole dry day after rain.
    18 
    19 For differential GPS, aim to have a base station nearby (within 20km) and ideally in center of the scene.  Base station data should be recorded at 2Hz
    20 
    21 Ideally choose a time with a good GPS constellation (lots of satellites, PDOP >= 4).
    22 
    23 Consider terrain and minimum target size to determine required point density.  Steep terrain may cause shadowing effects due to perspective.
    24 
    25 Consider reflectivity of surface - lighter surfaces need less laser power.  Too high a power means intensity overflows on the reflection, which mess up the range - AGC should deal with this for large areas but it should be considered in planning, particularly for small bright targets on a generally darker background.  Assume 10% reflectivity is typical.
    26 
    27 Recommended to do a figure 8 loop at the start and end of the data acquisitions to make the IMU happy.  Need one at the end for reverse navigation processing.
     13--------------------------
    2814
    2915== Overall system design and comments of note ==
     
    8672This apparently takes another week long training course.  We do have the basic software to do it but limited knowledge.  Basic process is to determine the camera parameters, correct and overlay the images, keeping ideally only the most central parts.  You then have to manually check through, especially along seams, and manually move the seam line in some instances (e.g. when perspective effects result in odd errors due to the seam hitting a tall building).
    8773
     74--------------------------
    8875
    8976== Recommendations ==
    9077
    9178Perform calibrations frequently at the start of the period to get a feel for how they hold.  Reduce down to fit circumstances over time.
     79
     80=== Mission planning considerations ===
     81
     82Water absorbs IR, so expect poor returns from wet surfaces.  Ideally one should wait for a whole dry day after rain.
     83
     84For differential GPS, aim to have a base station nearby (within 20km) and ideally in center of the scene.  Base station data should be recorded at 2Hz
     85
     86Ideally choose a time with a good GPS constellation (lots of satellites, PDOP >= 4).
     87
     88Consider terrain and minimum target size to determine required point density.  Steep terrain may cause shadowing effects due to perspective.
     89
     90Consider reflectivity of surface - lighter surfaces need less laser power.  Too high a power means intensity overflows on the reflection, which mess up the range - AGC should deal with this for large areas but it should be considered in planning, particularly for small bright targets on a generally darker background.  Assume 10% reflectivity is typical.
     91
     92Recommended to do a figure 8 loop at the start and end of the data acquisitions to make the IMU happy.  Need one at the end for reverse navigation processing.
     93
     94---------------------------
     95
     96= Processing =
    9297
    9398== Required items for processing ==
     
    105110 * lever arm measurements
    106111
    107 = Processing =
    108112== Extraction ==
    109113
     
    120124See other pages on navigation processing as they cover this already.
    121125
     126== General processing ==
     127
     128''Mark covered this better''
     129
     130-----------------------
    122131= QC =
    123132
     
    180189 * comparisons against GCPs
    181190   * requires the point cloud to be converted to a surface (
    182 
    183191
    184192