Changes between Version 3 and Version 4 of FAQ/azgcorrbend


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Timestamp:
May 18, 2012 5:30:14 PM (7 years ago)
Author:
benj
Comment:

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  • FAQ/azgcorrbend

    v3 v4  
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    33'''A:'''[[BR]]
    4 This means that the aircraft turned without turning off the sensor. Azgcorr was designed to process reasonably straight single survey lines and is not intended for use on flights including large turns - attempting to process such lines causes problems. There are two solutions to this:
     4This means that the aircraft turned without turning off the sensor. Azgcorr was designed to process reasonably straight single survey lines and is not intended for use on flights including large turns - attempting to process such lines causes problems. The present default is to continue if a bend is present after giving a warning message; if interpolation selected is -ic (bicubic), -il (linear) or -in (nearest neighbour) the run may fail or leave portions of the line unprocessed.
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    6 1. (Easy solution) Process the flightline with an extra "-bend" option to azgcorr. This will override the turn check and allow processing to proceed. Be aware that this may cause the processing to segfault, and if it doesn't then it may not produce correct positioning. You are advised to check your results against vectors or other known good data.
     6There are three solutions to this:
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    8 2. (Harder solution) Process the flightline in pieces and leave out the bit that's got the bend in it. The easiest way to do this is to process as in 1 above to determine where the bend is on the line, then use the scan line numbers given in the processing run and a bit of trial and error to cut out the bend using the -l option:
     81. (Preferred solution): Process the flightline with an extra "-bend -inf2" option to azgcorr. This will override the turn check and use fast nearest neighbour interpolation, which should be able to handle the turns.
     9
     102. (Secondary solution) If this fails or you don't want nearest neighbour interpolation, process the flightline with an extra "-bend" option to azgcorr (but not -inf2). This will override the turn check and allow processing to proceed. Be aware that this may cause the processing to segfault, and if it doesn't then it may not produce correct positioning. You are advised to check your results against vectors or other known good data.
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     123. (Harder solution) Process the flightline in pieces and leave out the bit that's got the bend in it. The easiest way to do this is to process as in 2 above to determine where the bend is on the line, then use the scan line numbers given in the processing run and a bit of trial and error to cut out the bend using the -l option:
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    1014azgcorr ... -l <start_line> <end_line> ...