Use this procedure to multilook SIR-C compressed data products.

Syntax

ENVI_DOIT, 'SIRC_MULTILOOK_DOIT', AZ_M=value, DIMS=array, F_NS=integer, F_NL=integer, FNAME=string array, LOOK=array, OFFSET=array, OUT_NAME=string, R_FID=variable, RANGE_M=value, SLH=array, TYPE={0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9}, XSTART=value, YSTART=value

Keywords

AZ_M

Use this keyword to specify the azimuth or y image size in meters.

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

F_NS

Use this keyword to specify the number of samples per line in the SIR-C image.

F_NL

Use this keyword to specify the number of lines in the SIR-C image.

FNAME

Use this keyword to specify a string array of compressed data products filenames for C and/or L bands, respectively. If you do not use a file, then set the array element to ''.

LOOK

Use this keyword to specify a two-element array of floating-point values representing the look factors to apply to the x and y directions for range and azimuth, respectively.

OFFSET

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

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.

RANGE_M

Use this keyword to specify the range or x image size in meters.

SLH

Use this keyword to specify an array of long integers indicating which files need to strip the line header. A value of 0 indicates that line header is not present, and a value of 1 indicates that the 12-byte SIR-C line header must be stripped. SLH must have the same number of elements as FNAME.

TYPE

Use this keyword to specify an array of SIR-C data product types for each of the files specified by FNAME.

  • 0: MLS quad-polarized
  • 1: MLC dual-polarized HH VV
  • 2: MLC dual-polarized HH HV
  • 3: MLC dual-polarized VH VV
  • 4: SLC quad-polarized
  • 5: SLC dual-polarized HH VV
  • 6: SLC dual-polarized HH HV
  • 7: SLC dual-polarized VH VV
  • 8: SLC single-polarized HH
  • 9: SLC single-polarized HH

XSTART

Use this keyword to specify the x offset of the input file.

YSTART

Use this keyword to specify the y offset of the input file.

API Version

4.2