Changes between Version 17 and Version 18 of Sensors/LeicaLIDAR/MikesNotes


Ignore:
Timestamp:
Aug 29, 2008 7:12:01 PM (11 years ago)
Author:
mggr
Comment:

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  • Sensors/LeicaLIDAR/MikesNotes

    v17 v18  
    2828
    2929Most Leica systems are mounted "laser backwards" (cables will be at the rear if this is so) - ensure that z=180 in the IPAS Pro aircraft tab.
     30
     31Streaky intensity images - "bad, contact support for guidance".  These will probably cause range errors due to the intensity variation, no idea what the cause would be as yet..
    3032
    3133=== Other error sources ===
     
    292294''Needs per click instructions as it's a bit clunky - I have some of these, but hopefully Mark has more''
    293295
    294 Note that Attune apparently crashes if you use >400MB files, and crashes plenty anyway - save often!
     296'''Note that Attune apparently crashes if you use >400MB files, and crashes plenty anyway - save often!  Do an initial run with just a few tie points to make sure the lines will work.'''
    295297
    296298First, classify the LAS files - the automatic process should only be used on ground points (largely to avoid perspective effects on buildings?)
     
    313315=== Selecting tie points ===
    314316
    315 Place tie points on the higher altitude lines only when you're really sure of them - they will always have a greater error due to the pixel size.
    316 
     317 * Better to have fewer good tie points than many bad ones
     318 * Focus mainly on the lower altitude lines
     319   * Place tie points on the higher altitude lines only when you're really sure of them - they will always have a greater error due to the pixel size.
     320 * Tarmac roads are good, but:
     321   * avoid paint on road (intensity problems and height difference)
     322   * choose continuous homogeneous areas
     323 * Avoid:
     324   * building corners (perspective)
     325   * grass (multiple returns, moves)
     326   * cars/people (moves)
     327   * areas with streaky intensity (likely to have ranging errors)
     328 * Try to select areas where you can use the nearby geometry to help you
     329   * e.g. follow straight road edges to where they intersect another feature, so you have more than just one pixel to guide you to the intersection point in other images
     330   * avoid using building edges (perspective shifts)
     331 * Location of tie points
     332   * Focus mainly in the core intersection area
     333   * Points around nadir
     334   * Points around the edges of the swath
     335   * Some generally scattered around
     336   * Some outside the core intersection area
     337   * Try to include some on slopes(?)
    317338--------------
    318339= Random snippets =