File Descriptions

For more information see the ROI_pac internals document from the Short Course available in PDF

File Types

In outline, the files output by ROI_PAC have 4 basic types:

1) ASCII files used for input or output by programs (suffixes: .out, .in, .off: more details below)

2) Binary files as real or complex files (see below) • RMG format (Names for JPL radar pioneer Richard M. Goldstein) are made up of real*4 (32 byte) numbers in two arrays side-by-side. The two arrays often show the “magnitude” of the radar image and the “phase” – although not always (sometimes the “phase” is the correlation. The length and width of each array are given as lines in the metadata (.rsc) file. Thus the total width of the binary file is (2 * width) and the data are stored as (Magnitude, magnitude, magnitude…, Phase, Phase, Phase,…) • complex or c8 files contain real and imaginary values that are stored in the binary file as (real, imaginary, real imaginary, etc.)

3) ASCII files associated with each binary file containing metadata (end with .rsc – resource file); and a record of the changes made to the metadata file (.rsc.hst – history file)

4) ASCII log files that record the commands that have been run in each directory where ROI_PAC is run. The log files provides a record of the commands that have been run and the times that these were run. During debugging you can often just copy and paste these commands onto the command line modifying one or more values. The log1 file shows the information that was written out by the scripts to the screen, but unfortunately it usually does not include error messages.

Input file types

  1. *.proc = ASCII text file specifying parameters used in processing and there are two main types: int*.proc files for creating the interferograms (required and the suffix is allowed to be different) and optional roi.proc or (DATE).proc files that are used to create the slc’s. See Appendix X for details on the different parameters that can be set.
  2. *.dem = binary file with digital elevation model in lat-long or UTM coordinates, signed integer 2-byte values (in meters unless scaling specified). An important question to consider when comparing InSAR results to GPS or others is whether the heights in the DEM file refer to heights relative to the ellipsoid or the Geoid (SRTM refers to Geoid heights). The .dem and .dem.rsc file can be automatically generated by the script get_SRTM.pl available at roipac.org/ContributedSoftware or you can create your own files. The format for the .rsc file is as follows:

• WIDTH number of columns

• FILE_LENGTH number of rows

• X_FIRST longitude of upper left corner (does it refer to center of upper left pixel?)

• Y_FIRST latitude of upper left corner (does it refer to center of upper left pixel?)

• X_STEP longitude pixel size in degrees for latlon, meters for UTM

• Y_STEP latitude pixel size in degrees for latlon, meters for UTM

• X_UNIT degrees or meters

• Y_UNIT degrees or meters

Output file types (organized by suffix)

  1. "file.type".rsc = ASCII text file containing metadata about "file.type" or
  2. "file".rsc = ASCII text file with other metadata such as baseline for interferogram pair
  3. *.int = complex real 8-byte binary file containing real and imaginary parts of the interferogram (can also be read as real or float values band interleaved by pixel)
  4. *.amp = binary file with amplitudes of the two SAR images used to form an interferogram, real 4-byte values band interleaved by pixel (can also be read as complex 8-byte values)
  5. *.off = ASCII text file of offsets measured between two images
  6. *.in = ASCII text file created by ROI_pac scripts used as input for a compiled program
  7. *.out = ASCII text informational output of a program
  8. *.hgt = binary file with simulated SAR amplitude image and elevation in radar coordinates, real 4-byte values band interleaved by line (BIL or “rmg”)
  9. *.slc = complex real 8-byte binary file containing real and imaginary parts of the single-look complex (SLC) image (and multilooked versions of the SLC)
  10. *.cor = binary file with average amplitude of SAR images used to form an interferogram and correlation measure of coherence, real 4-byte values band interleaved by line (BIL or “rmg”)
  11. *.raw = binary file of raw data, I,Q (see section X for explanation) 1-byte integer values for each echo sample
  12. *.aff = ASCII text file of affine transformation to map simulated image to actual SAR image
  13. *.unw = binary file with SAR amplitude image and unwrapped phase, real 4-byte values band interleaved by line (BIL or “rmg”). The units in the file are radians and can be converted to cm by multiplying by the radar wavelength and dividing by 4*pi. NOTE: phase change values in this file are relative – that is zero radians of phase change could actually be -1 m, +1 m, or some other value that must be otherwise constrained.
  14. *.flg = binary file with flags used and resulting from unwrapping with standard unwrapper, 1-byte values with flags set in bits
  15. *.msk = binary file with SAR amplitude image and coherence with zeros in masked out areas, real 4-byte values band interleaved by line (BIL or “rmg”)
  16. *.trans = binary file with inverse mapping transformation from SAR to DEM coordinates, two bands are range and azimuth pixel locations of SAR for each DEM pixel, real 4-byte values band interleaved by line (BIL or “rmg”)

Output file types (organized by prefix)

  1. *rlks* Specifies the number of range looks taken from the full resolution interferogram or, for a geocoded file, from the resolution of the full resolution geocoded file
    1. filt_* means that the file has been filtered by the filter.pl script
    2. *-sim* means that the simulated topographic interferogram has been removed
    3. flat_* the file has been flattened (a.k.a. orbital effects have been removed) geo_* file has been geocoded
  2. SIM_* The DEM has been converted to radar coordinates (simulated interferogram) using orbital information but no fine adjustment of the position has been made (see radar_*)
  3. radar_* The DEM has been converted to radar coordinates (simulated interferogram) using orbital information and a fine adjustment of the position has been made (this file is created after SIM_*)
    • radar_*.unw is created by diffnsim.pl and includes the orbital & topographic effects radar_*.hgt is created by rect.pl and includes only the topographic effects

a. ramp_* The orbital phase ramp created by diffnsim.pl with no topographic effects

a. *SIM* or *ODR* or *PRC* or *HDR* means that the orbital effects have been removed using the given type:

FileDescriptions (last edited 2012-07-16 14:07:37 by MattPritchard)