Contacted by Bill handing over Mohammed's processing problem. He was having difficulties with DEMs (specifically formatting.

Following an updated azgcorr, Johanna is now working on using external BIL files (note previous support ticket #56 for background).

We have been trying to run azgcorr with a BIL file as we have now  
atmospherically corrected the CASI data (through FLAASH in ENVI, with good
results), but the command is not running
as expected. In the PDF documentation it states that we should use the  
-Bi command to specify the location of the BIL file and the -B command  
to specify its parameters. The -B command is stated as having 5
parameters:

option:
  -B  b t s o f

  BIL or BSEQ file content details
b = total bands on file
t = number type on file, 0= uint16, 1= float32
s = scale
o = offset to convert B file values for geom correction and saving as
uint16, v = p * s + o
f = &#64257;ll value for bad pixels; good pixels are < f

  if f = 0 the default values of 0 and 0xffff (uint16) or 10e30
(&#64258;oat32) are assumed
requirement:
  MUST be used if -Bi or -Bs are useddefaults:
  b NONE; s = 1.0; o = 0.0

When we execute the following commands (it works correctly without the  
-B and -Bi) we get the following error message:

./bin/azgcorr -v -mUK99 ./misc/osgb02.cgrf -e ../DEM/
vrynwy_dem_2m_ascii.txt -ed 1 8165 7530 291585.9219 314915.0528
307913.9219 329973.0538 2 -p 2 2 -1 ./lev1/c219011b.hdf -3 ./lev3/ 
c21013a.hdf  -B 15 1 1.0 0.0 0  -Bi ./lev2/c219012a_refl

-----------------------------------------------------------------------
azgcorr  -- ver: 4.8.7-lin Jan  2 2008   (C) Azimuth Systems UK 1996,  
2008


** parameter: ./lev2/c219012a_refl  does not start with:  -
**     and may be incorrect or out of sequence


After 'playing' with the commands experimenting with the order,
although stated in the documentation it is unimportant, we found that  
when an extra parameter (6 rather than 5) is added to the -B command   is
attempts to run but now fails with the following error.

./bin/azgcorr -v -mUK99 ./misc/osgb02.cgrf -e ../DEM/
vrynwy_dem_2m_ascii.txt -ed 1 8165 7530 291585.9219 314915.0528
307913.9219 329973.0538 2 -p 2 2 -1 ./lev1/c219011b.hdf -3 ./lev3/ 
c21013a.hdf  -B 15 1 1.0 0.0 0 0  -Bi ./lev2/c219012a_refl

-----------------------------------------------------------------------
azgcorr  -- ver: 4.8.7-lin Jan  2 2008   (C) Azimuth Systems UK 1996,  
2008

data recorded in year: 2006  date: 07/08/2006
CCD type [1]: CASI scanner details and data

HDF level 1 input file: ./lev1/c219011b.hdf
CCD CApsfov table from hdf file with: 512 entries
Image input BIL/BSEQ file: ./lev2/c219012a_refl
?? warning: BIL/BSEQ file size is not consistent with HDF details
?? expected size (from HDF): 15665152 bytes, actual size (BIL/BSEQ):  
117488640 bytes

Could you confirm the commands and their parameters or is there
something we are obviously doing wrong?

Peter Land suggested altering azgcorr to allow L1 files to be opened read-only. Currently they are opened read-write, which causes problems if they are on / were copied from read-only media.