openairsar

(rtools/openairsar.m)

Function Synopsis

aline = readline(data_fid,field_width)

Help text

function [data,structure] = openairsar(filedir,filecode,frequency,start_line,load_lines)

 Open compressed AirSAR data using standard format. Tested on processor v2.3 (old
 header format) and v6.35 (new header format)

 DUE TO THE COMPRESSION, THE DERIVED COVARIANCE MATRICES MAY NOT ALL BE POSITIVE DEFINITE

 DATA is in the form data.hhhh data.hvhv data.vvvv data.hhhv data.hvvv data.hhvv
 each as a matrix of [range_samples, time_lines] ordered from near_range,first_time = 1

 If STRUCTURE is passed into the routine, an attempt at converting the parameter file
 into a matlab structure will be made. If there are any errors, the routine shoul
 recover gracefully - there seems to be slight variation in AirSAR formats that I may
 have missed.

 If the data is new, you may want to also try openairsar_new.m which processes the
 associated hdxxxx.log files in a much simpler way. The major difference is the way
 the header parameters are interpreted into a Matlab structure, the data is processed
 identically.

 If the data is old, the old header will be read into structure.OLD_HEADER as a
 character array. The end of this may be filled with garbage - I don't know what the
 format is. Also the structure titles may be slightly different e.g.:
  New Format: structure.AZIMUTH_PIXEL_SPACING__METERS_
  Old Format: structure.AZIMUTH_PIXEL_SPACING___METERS__  {2 additional _ }

 If structure is passed into the routine, and the data uses the new header format,
 an attempt to obtain the radiometric correction vector will be made - this is not
 always present but will be output as structure.RADVEC_HH , structure.RADVEC_HV or
 structure.RADVEC_VV as size [range_samples,1] However, some files are limited to
 19600 bytes (i.e. a maximum of 2250 range samples) bytes due to a problem up to
 ENVI v3.5/IDL v5.5 - A warning will be output when this is detected.

 structure.NAME_OF_HEADER will contain the name of the last header processed

 note that start_line goes from 1.

 source is pdf's referenced at:
 http://airsar.jpl.nasa.gov/documents/instrument.htm
[1] Airsar Integrated Processor Documentation Data Formats v0.15
[2] Understanding Synthetic Aperture Radar Images, Chris Oliver, Shaun Quegan, 
     1998, Artech House

 Part of the Matlab Radar Toolbox v0.11 by Glen Davidson at www.radarworks.com
 Please acknowledge use of this toolbox in any publication or software.
 This header must be retained in any derivative work

Cross-Reference Information

segmentation_demo             rtools/segmentation_demo.m