Changes between Version 25 and Version 26 of Processing/LidarCalibrationProcedure


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Timestamp:
Aug 17, 2012 10:47:15 AM (7 years ago)
Author:
emca
Comment:

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  • Processing/LidarCalibrationProcedure

    v25 v26  
    4545   * Part of interest will be the area where all flight lines overlap.
    4646
    47 3. Ground classification needs to be performed on the files before tie pointing in Attune. But to load the ATN.LAS files into Terrascan we need to first import them into Attune to convert them. To do this we need to start the Attune software
     473. Converting the ATN.LAS files to bin files. Ground classification needs to be performed on the files before tie pointing in Attune. But to load the ATN.LAS files into Terrascan we need to first import them into Attune to convert them. To do this we need to start the Attune software
    4848 * We do this so that we only use points on the ground in the tie pointing (since we don't want errors due to perspective or shadowing)
    4949 * In Attune - Add ALS data -> add the real ATN.LAS files from the ALSPP output
     
    5252   * 'a' centres the image
    5353   * '+/-' to zoom in/zoom out
    54  * There should now be some files with .bin extension- they are created automatically alongside the .pngs. These can be imported into Terrascan (which can read .bin as well as .las) for ground classification.
    55  * Ground classification procedures can be found [wiki:Sensors/LeicaLIDAR/MashUp#Groundclassification here]
     54 * There should now be some files with .bin extension- they are created automatically alongside the .pngs.
    5655
    57 4. Once the data have been ground classified re-start Attune and tie point the data
     564. Ground Classification [[BR]]
     57 To ground classify the *.bin files use lasground from LASTools. This tool has a 1.5million point limit so the *.bin files need to be split up first into smaller files. Note this process can be easily scripted.
     58 * run las2las with the option -subseq:
     59 e.g. las2las -i lasfile1.bin -subseq 0 1500000 -o lasfile1_a.bin; las2las -i lasfile1.bin -subseq 1500000 3000000 -o lasfile1_b.bin etc.
     60 * run lasground.exe -i lasfile1_a.bin -o lasfile1_a_gr.bin
     61 * run lasmerge -i lasfile1*gr.bin -o ground_classified/lasfile1.bin
     62 * las2las -i ground_classified/lasfile1.bin -o ground_classified/lasfile1.LAS
     63 * replace the attune created *.bin files with the ground classified ones.
     64 
     65 Check the ground_classified LAS files in LAG to make sure that the classification has worked as expected. You can alter the settings used in lasground e.g. using -step, -spike. See the lasground Readme for more info.  [[BR]]
     66
     67
     68Note: Ground classification procedures using TerrsScan can be found [wiki:Sensors/LeicaLIDAR/MashUp#Groundclassification here].
     69
     70
     71
     725. Tie point the data [[BR]]
     73   Once the data have been ground classified re-start Attune and tie point the data
    5874 * Now select tie points. We use streets for tie points since these should be on the ground so no (little) effects due to look angles and also has slow varying topography
    5975   * Open tie point editor in Attune.
     
    8298   * When happy save the solution - also note down roll, pitch and heading values in case of crashes
    8399
    84 5. Return to ALS Post Processor
     1006. Return to ALS Post Processor
    85101 * Add the Pitch, Roll and Heading values into the boresight calibration dialog.
    86102 * Change output to LAS (not attune)
     
    88104 * Re-run the processing
    89105
    90 6. Now analyse the results in LAG or !TerraScan
     1067. Now analyse the results in LAG or !TerraScan
    91107 * Check profiles etc for misaligning flightlines.
    92108 * To load all flightlines will probably need to use a fence (this is like a region of interest)
     
    96112 * Also possible to check for errors by re-ordering points by elevation
    97113
    98 7. The boresight parameters can be manually twiddled (rather than using Attune) by reprocessing in ALS, changing the R,P,H values one at time.  Only process parts of the flightlines for speed benefits.
     1148. The boresight parameters can be manually twiddled (rather than using Attune) by reprocessing in ALS, changing the R,P,H values one at time.  Only process parts of the flightlines for speed benefits.
    99115
    100 8. When happy with the results save the ALS Post Processor settings to a .reg file for future reference.
     1169. When happy with the results save the ALS Post Processor settings to a .reg file for future reference.
    101117-------
    102118== Range Calibration ==