Changes between Version 2 and Version 3 of Processing/Procedures/AlsprocAutoPitchRoll


Ignore:
Timestamp:
May 22, 2015 2:53:47 PM (4 years ago)
Author:
dac
Comment:

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  • Processing/Procedures/AlsprocAutoPitchRoll

    v2 v3  
    1 = Automatically Determining the best Pitch and Roll =
     1= Automatically determining the best Pitch and Roll =
     2
     3'''Note: This is an experimental procedure, you still need to check the values in LAG and process the final data in ALSPP. Keep a note of any problems and pass them onto dac'''
     4
     5If you are using this to process data after day 2014/238 you need to use the calibration file '/users/rsg/arsf/calibration/2014/lidar/20140826/2014_238_calibration_no_fla.reg' in ALSPP, as this doesn't have a FLA correction so ''should'' produce the same values as alsproc - check this though.
    26
    37Currently the scripts are still in development and are not available on the arsf path.
     8
    49You need to load them using:
    510
     
    1116The general procedure is similar to that of alsproc, for which there is a guide [wiki:Procedures/AlsprocProcessing here].
    1217
    13 The script is 'calc_roll_offsets.py' pass in the '-h' flag to get more information on usage.
     18A couple of changes are required to the config file:
     19
     20* Set start, end and increment values for pitch / roll / heading.
     21{{{
     22roll-start = -0.0039
     23roll-end = -0.0041
     24roll-inc = -0.00001
     25}}}
     26You can vary multiple parameters at the same time but the total number of increments must not exceed 100.
     27
     28* For long lines set a minimum and maximum time to process
     29{{{
     30time-min = 558224
     31time-max = 558249
     32}}}
     33Ideally covering an area with good features for the comparison (i.e., buildings and hard surfaces).
     34
     35* Only process the first returns
     36{{{
     37first-return-only = true
     38}}}
     39
     40* Only set two filightlines at once to process
     41
     42Once the parameters have been set in the config file you can run the script 'calc_roll_offsets.py' (pass in the '-h' flag to get more information on usage).
     43
     44Basic usage will be something like:
     45{{{
     46calc_roll_offsets.py -d out_diff_images_folder --plot out_plot.pdf 2014303.cfg
     47}}}
     48
     49The script will run alsproc for every increment for each line then compare the two (or more) lines for each increment and return the best match.
     50Note this might not be the best value for the flights, just the minimum for the range of values provided.
     51
     52To get more information look at the plot. Ideally there should be a minima somewhere between the minimum and maximum values. If it is still decreasing you should change the range. I good practice is to start with a large range and bigger increments to get a rough idea of the correct values then run again with a narrower range and smaller increments. It's a good idea to check the LAS files as well to make sure everything looks OK.
     53
     54If you want to run multiple increments in parallel (on your local machine) you can do so with the following environmental variable:
     55
     56{{{
     57export RUN_ALSPROC_INC_PARALLEL=YES
     58}}}