Batch Processing single band raster to create multi spectral images using arcpy.CompositeBands_management?

Question

I am kind of new to python but I am trying to batch process single band raster images to create multispectral imageries using arcpy Composite Bands. I have 24 single band rasters (Bands 1 - 3 ) all saved in a single folder which would create 8 composite images after its done. Fortunately the bands are in sequential order for each set, so I can input every three images without having to order them. So far I have:

arcpy.env.workspace = "C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out"

   direc = r"C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out"
out_raster = "C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out\\Composite_Bands"

i = 0
rasters = arcpy.ListRasters("*", "JP2")
for raster in rasters:
    i+=1
    arcpy.CompositeBands_management(raster, out_raster + "\\" + out)

Can you offer any suggestions or ideas?

Answer 1

Your problem is on your iteration.. the composite bands command is run for each image. Try it this way:

import arcpy,os

arcpy.env.workspace = "C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out"
direc = r"C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out"
out_raster = "C:\\Users\\Vinny\\Desktop\\Sentinel2_Scripts\\Unzipped\\Test_Out\\Composite_Bands"

rasters = arcpy.ListRasters("*", "JP2")
rList = []
for raster in rasters:
    rList.append(os.path.join(direc,raster))
    if len(rList) == 3:
      arcpy.CompositeBands_management(rList, out_raster + "\\" + out) #what is the value of out?
      rList = [] # a new empty list

This holds back the running of CompositeBands until 3 images are present in the list and then resets the list back to empty. Note that nowhere in your code is the value of out set, I assume it's on a line that's been removed.

The example for CompositeBands has a semicolon separated string but the doc indicates that a python list is acceptable for the inputs. If the input is truly a semicolon separated list you can use string.join(rList,';') to convert the list to a string with delimiters (don't forget to import string first).