ANSI-C program: hgt_map.c
NAME
hgt_map - Uses the unwrapped interferometric phase and baseline
geometry to generate a height map and ground range map in slant
range geometry.
SYNOPSIS
hgt_map <unw> <SLC_par> <OFF_par>
<baseline> <height> <gr> [ph_flag] [loff]
[nlines] [SLC2R_par]
| <interf_unw> | (input) unwrapped interferometric phase |
| <SLC_par> | (input) ISP parameter file for the reference SLC |
| <OFF_par> | (input) ISP interferogram/offset parameter file |
| <baseline> | (input) baseline parameter file |
| <height> | (output) height relative to the WGS-84 ellipsoid (in slant range geometry) |
| <gr> | (output) cross-track ground range relative to the WGS-84 ellipsoid (in slant range geometry) |
| [ph_flag] | restore range phase ramp (default=0: do not restore 1: restore) |
| [loff] | offset to starting line for height calculations (default=0) |
| [nlines] | number of lines to calculate (enter - for default: to end of file) |
| [SLC2R_par] | (input) parameter file of resampled SLC, required if SLC-2 frequency differs from SLC-1 |
EXAMPLE
hgt_map 1352_1610.unw 1352.par 1352_1610.off 1352_1610.base
1352_1610.hgt 1352_1610.gr
DESCRIPTION
hgt_map reads the phase
unwrapped interferogram and the baseline geometry and
reconstructs the terrain height and cross track position for each
pixel and on an ellipsodial (WGS84) Earth model. The unwrapped
phase is a measure of the propagation path length difference
between the received signals used to generate the interferogram.
This is combined with the baseline data for each line in the
image to calculate the look vector from the radar to the point on
the ground.
The hgt_map program also requires the SLC parameter file of the reference image and the offset interferogram parameter file to reconstruct the interferometric DEM data. The two resulting images (height, ground range) are written into separate files. Display and generation of images of the resulting height map (in slant range geometry) together with the image intensities is supported by programs rashgt and dishgt.
In the case where the center radar frequencies differ for the SLCs used to generate the interferogram (e.g. ERS-ENVISAT) then the parameter file of the second SLC must be specified on the command line.