Changes between Version 23 and Version 24 of Processing/LidarCalibrationProcedure


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Timestamp:
Aug 2, 2012 10:47:37 AM (7 years ago)
Author:
emca
Comment:

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  • Processing/LidarCalibrationProcedure

    v23 v24  
    8888 * Re-run the processing
    8989
    90 6. Now analyse the results in Terrascan
     906. Now analyse the results in LAG or !TerraScan
    9191 * Check profiles etc for misaligning flightlines.
    9292 * To load all flightlines will probably need to use a fence (this is like a region of interest)
     
    135135 * Finally load in all flights into Terrascan (within a fence if memory issues) and check them (ideally along a stream because this has a “good” profile) Can use the travel path tool in Terrascan for comparing cross sections along a path.
    136136
    137 5. Check for offset between bank A and bank B
    138  * Leica have advised that *some* systems have an offset between bank A and bank B. To check for an offset process a single line using only returns from bank A then using only returns from bank B (ALSPP: Filters > Pre-Proc Filters > Filter Range Bank A/B).
    139  * Load the results in !TerraScan and check for any elevation difference.
    140     * If there is none then great.
    141     * If a consistent offset is visible then adjust all the values for bank B by this offset. Re-run the line again and check the result.
     137
     138
    142139-------
    143140== Final validation ==
     
    147144 * To check the Torsion look at cross sections of high altitude cross flight. Flat roads and grassy areas are good. Look for “smiles” in the data. This can be done by looking at the centres of the edges of the overlapping area
    148145 * May also be able to do this by re-ordering points by elevation
    149 2. Save the final ALS PP options to a .reg file
     146
     1472. Check for offset between bank A and bank B
     148 * Leica have advised that *some* systems have an offset between bank A and bank B. To check for an offset process a single line using only returns from bank A then using only returns from bank B (ALSPP: Filters > Pre-Proc Filters > Filter Range Bank A/B).
     149 * Load the results in LAG or !TerraScan and check for any elevation difference.
     150    * If there is none then great.
     151    * If a consistent offset is visible then adjust all the values for bank B by this offset. Re-run the line again and check the result.
     152
     1533. If full waveform data has been collected then the Trigger Delay values need to be checked
     154 * Use LasHistoViewer to verify that the LAS file is suitable for calibration purposes
     155     * check the AGC activity is not jumping around or saturated - value of ~150
     156     * 1 volt is good target for timing offset
     157     * Intensity ~ 60-80
     158     * waves where there is one discrete return only
     159 * In ALSPP > Ultilies > Load Wave Viewer
     160    * display by time and volts 
     161    * the peak of the FW signal and the discrete point should coincide
     162    * zoom in and manually calculate the difference in time between the peak of the FW and the first discrete return
     163    * under Options there is a box where the trigger delay can be entered - this can be used to assist in visualising the calibration
     164    * repeat until an accurate result is obtained
     165    * check for several waves over varying parts of the flightline and calculate the average value
     166    * above and below TPR (transition pulse rate) are independent and calculated separately
     167       * below TPR, less than 100,000 Hz
     168       * above TPR, greater than 100,000 Hz 
     169 * Make a note in the ticket if either of the trigger delay values have been validated
     170
     1714. Save the final ALSPP options to a .reg file
     172
     173
    150174------------
    151175== Once finished ==