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

Timestamp:

May 22, 2015, 2:53:47 PM (10 years ago)

Author:

dac

Comment:

--

Processing/Procedures/AlsprocAutoPitchRoll

@@ -1 @@
-= Automatically Determining the best Pitch and Roll =
+= Automatically determining the best Pitch and Roll =
+
+'''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'''
+
+If 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.
 
 Currently the scripts are still in development and are not available on the arsf path.
+
 You need to load them using:
 
@@ -11 +16 @@
 The general procedure is similar to that of alsproc, for which there is a guide [wiki:Procedures/AlsprocProcessing here].
 
-The script is 'calc_roll_offsets.py' pass in the '-h' flag to get more information on usage.
+A couple of changes are required to the config file:
+
+* Set start, end and increment values for pitch / roll / heading. 
+{{{
+roll-start = -0.0039
+roll-end = -0.0041
+roll-inc = -0.00001
+}}}
+You can vary multiple parameters at the same time but the total number of increments must not exceed 100.
+
+* For long lines set a minimum and maximum time to process
+{{{
+time-min = 558224
+time-max = 558249
+}}}
+Ideally covering an area with good features for the comparison (i.e., buildings and hard surfaces).
+
+* Only process the first returns
+{{{
+first-return-only = true
+}}}
+
+* Only set two filightlines at once to process
+
+Once 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).
+
+Basic usage will be something like:
+{{{
+calc_roll_offsets.py -d out_diff_images_folder --plot out_plot.pdf 2014303.cfg
+}}}
+
+The 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.
+Note this might not be the best value for the flights, just the minimum for the range of values provided.
+
+To 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.
+
+If you want to run multiple increments in parallel (on your local machine) you can do so with the following environmental variable:
+
+{{{
+export RUN_ALSPROC_INC_PARALLEL=YES
+}}}