Changes between Version 2 and Version 3 of Processing/Splitting

Timestamp:

Aug 19, 2014, 10:15:13 AM (10 years ago)

Author:

dap

Comment:

Added in instructions for how to split Fenix flightlines

Processing/Splitting

@@ +1 @@
+= Splitting Flightlines =
+
+Some PIs will request that processed flight lines are split in to smaller lines, especially if the files generated are of a large size.
+
+== Fenix Splitting ==
+
+It is recommended that you do this after you have found the correct SCT offset values and are ready to generate the final files, as the splitting is done by aplcal when you submit the jobs to the grid. The splitting of the flight lines can be done by following this process:
+
+1. Find out the number of smaller segments the PI wants the flight lines split in to. This could be in the ticket or in emails. Ask someone if unsure.
+1. If it is not already there, append {{{cal_args_extra = -lines}}} to each flight line section of the config file. This tells aplcal which raw lines to process for this particular flight line section, using the {{{-lines}}} argument of aplcal.
+   a. '''Note:''' If there is a global {{{cal_args_exrtra = }}} record in the config file (i.e. in the {{{[DEFAULT]}}} section, at the top of the file), this will be overridden by ones local to flight lines. Therefore, you will need to copy the arguments from the global section in to each flight line section to overcome this.
+1. Copy and paste each flight line section in the hyperspectral processing file <number of segments required> -1 times below the original flight line section so that the number of sections for each line is equal to the number of segments required by the PI.
+1. Divide the number of lines in each raw header file (the {{{lines}}} record in the raw header files (found in .../<root project directory>/hyperspectral/fenix) by the number of segments required and round it up/down to something sensible.
+1. After the {{{cal_args_extra = -lines}}}, put in the numbers of the raw flight lines to process. 
+   a. For the first one, this will be 1 (the first flight line) and the number you obtained in the previous step. 
+   a. If no overlap is required, the next section should be double the result, and so on. If an overlap is required, the first number used in the latter of the two should be <overlap in metres> less than the second number used in the section before it.
+1. Change the header of each flight line section so that the numbers in the section headers are sequential, and change the {{{line_id}}} and {{{line_number}}} fields to match this.
+1. Change the {{{raw_filebase}}} in each flight line section so that they point to the raw files. Do this by changing what's already there to {{{raw_filebase = %(fenix_filebase)s-<original line number>}}}. You can find this out by doing <new flight line number> / <number of sections required by PI>, and rounding it up.
+
+Below is part of an example config file that was used for splitting hyperspectral data. In this example, each flight line was split in to three segments and used an overlap of 500m.
+
+{{{
+[fenix_-1]
+process_line = false
+line_id = -1
+line_number = 01
+altitude = 2037
+airspeed = 137
+track = 102.0
+raw_filebase = %(fenix_filebase)s-1
+output_filebase = f%(julian_day)s%(sortie)s%(line_number)s
+sct = 0.98
+cal_args_extra = -lines 1 8000
+
+[fenix_-2]
+process_line = false
+line_id = -2
+line_number = 02
+altitude = 2037
+airspeed = 137
+track = 102.0
+raw_filebase = %(fenix_filebase)s-1
+output_filebase = f%(julian_day)s%(sortie)s%(line_number)s
+sct = 0.98
+cal_args_extra = -lines 7500 16000
+
+[fenix_-3]
+process_line = false
+line_id = -3
+line_number = 03
+altitude = 2037
+airspeed = 137
+track = 102.0
+raw_filebase = %(fenix_filebase)s-1
+output_filebase = f%(julian_day)s%(sortie)s%(line_number)s
+sct = 0.98
+cal_args_extra = -lines 15500 24557
+
+[fenix_-4]
+process_line = true
+line_id = -4
+line_number = 04
+altitude = 1922
+airspeed = 141
+track = 282.0
+raw_filebase = %(fenix_filebase)s-2
+output_filebase = f%(julian_day)s%(sortie)s%(line_number)s
+sct = 0.96
+nav2_args_extra = -force
+cal_args_extra = -lines 1 8000
+
+[fenix_-5]
+process_line = false
+line_id = -5
+line_number = 05
+altitude = 1922
+airspeed = 141
+track = 282.0
+raw_filebase = %(fenix_filebase)s-2
+output_filebase = f%(julian_day)s%(sortie)s%(line_number)s
+sct = 0.96
+nav2_args_extra = -force
+cal_args_extra = -lines 7500 16000
+
+}}}
+
 == Splitting LiDAR point clouds ==
-== Discrete LiDAR ==
+=== Discrete LiDAR ===
 
 In the case of purely discrete point clouds we can use lasmerge to produce equal divided files.
@@ -14 +100 @@
 Use -o to specify the number of seconds of overlap, this can be used with the airplanes ground speed to calculate overlap. For instance 7 seconds 140 knots will result in an overlap of 504 metres (7 seconds * 72 m/s). Give the script a fraction for the number of lines to divide the line into, I usually just give it 3.
 
-== Full Waveform ==
+=== Full Waveform ===
 
 Full wave form data cannot use the script above. Unfortunately you will need to produce this using alspp and its fence feature.