Use this procedure to calculate phase images from an AIRSAR compressed stokes matrix.

Syntax

ENVI_DOIT, 'AIRSAR_PHASE_IMAGE_DOIT' [, /DEGREES], DIMS=array, FNAME=string array, FNL=integer, FNS=integer, GENFAC=array, /IN_MEMORY, OFFSET=array, OUT_BNAME=string array, OUT_NAME=string, R_FID=variable

Keywords

DEGREES (optional)

Set this keyword to output the phase images in degrees. The default is radians.

DIMS

The “dimensions” keyword is a five-element array of long integers that defines the spatial subset (of a file or array) to use for processing. Nearly every time you specify the keyword FID, you must also specify the spatial subset of the corresponding file (even if the entire file, with no spatial subsetting, is to be processed).

  • DIMS[0]: A pointer to an open ROI; use only in cases where ROIs define the spatial subset. Otherwise, set to -1L.
  • DIMS[1]: The starting sample number. The first x pixel is 0.
  • DIMS[2]: The ending sample number
  • DIMS[3]: The starting line number. The first y pixel is 0.
  • DIMS[4]: The ending line number

To process an entire file (with no spatial subsetting), define DIMS as shown in the following code example. This example assumes you have already opened a file using ENVI_SELECT or ENVI_PICKFILE:

  envi_file_query, fid, dims=dims

FNAME

Use this keyword to specify a string array of compressed stokes matrix filenames for C, L or P bands. A phase image will be calculated for each element in FNAME.

FNL

Use this keyword to specify the number of lines in the AIRSAR image.

FNS

Use this keyword to specify the number of samples per line in the AIRSAR image.

GENFAC

Use this keyword to specify an array of COMP SCALE FACTORS for each of the files specified by FNAME.

IN_MEMORY

Set this keyword to specify that output should be stored in memory. If you do not set IN_MEMORY, output will be stored on disk and you must specify OUT_NAME (see below).

OFFSET

Use this keyword to specify an array of long integers representing header offsets for each of the files specified by FNAME.

OUT_BNAME

Use this keyword to specify a string array of output band names.

OUT_NAME

Use this keyword to specify a string with the output filename for the resulting data. If you set the keyword IN_MEMORY, you do not need to specify OUT_NAME.

R_FID

ENVI Classic library routines that result in new images also have an R_FID, or “returned FID.” This is simply a named variable containing the file ID to access the processed data. Specifying this keyword saves you the step of opening the new file from disk.

API Version

4.2