Gamma DIFF & GEO Reference Manual

dem_RDC_list

NAME
dem_RDC_list - generate coordinate lists in Range-Doppler Coordinates (RDC) and DEM coordinates using a lookup table.

SYNOPSIS
dem_RDC_list <DEM_par1> <gc_map> <MLI_par> <mask> <clist_MAP> <clist_RDC> <DEM_par2> <s_north> <s_east>

<DEM_par1>	(input) DEM/MAP parameter file associated with the lookup-table
<gc_map>	(input) geocoding lookup table
<MLI_par>	(input) ISP image parameter file of MLI image associated with the geocoding lookup table
<mask>	(input) mask file in SUN raster of BMP format to mask out regions in clist (enter - for none)
<clist_MAP>	(output) list of x,y pixel coordinates in the geocoded MLI image (text format)
<clist_RDC>	(output) list of x,y pixel coordinates in the reference SLC image geometry (Range-Doppler Coordinates) (text format)
<DEM_par2>	(output) DEM/MAP parameter file associated with clist_MAP
<s_north>	northing sub-sampling factor (int) (default: 10)
<s_east>	easting sub-sampling factor (int) (default: 10)

EXAMPLE
dem_RDC_list dem_seg_par geo/19970924_0.map_to_rdc 19970924_seg.mli.par geo/19970924_gec.mli.mask.ras clist_MAP clist_RDC offset.dem_par 4 4

DESCRIPTION
dem_RDC_list is used to generate a list of points in range-Doppler coordinates of a uniformly spaced raster in a map projection coordinate system. A list of the coordinates of these points in northing line and easting pixel is also generated. This program generates the coordinate lists used by offset_pwr_list to measure offsets on a uniform raster in the map coordinate system using as input a pair of SLC images. dem_RDC_list uses the gc_map lookup-table to calculate the slant-range and azimuth pixel numbers in the range-Doppler coordinate system. The lists are in text format and consist of pairs of range pixel and azimuth line numbers.

The user can specify a mask in SUN raster or BMP format that is an overlay of the map coordinate image. Only points that lie within the non-zero values of the mask will be written to the output point lists. The positions of the points are specified using the DEM parameter file of a geocoded MLI image with geometry specified by the MLI_par parameter. The gc_map command line value is the lookup-table relating the MLI image and the geocoded image Typically an offset measurement is not required at every pixel in the geocoded image. Therefore northing and easting sub-sampling factors s_north and s_east can be specified on the command line. A DEM parameter file that describes the points in the clist_MAP is generated taking into account these sub-sampling factors. A map image shown the sample locations can be created using ras_clist.

The program prints out the unit vectors in the direction of slant range and azimiuth expressed using unit vectors in the East, North, and Up for a set of selected locations. The deformation measurements preformed by offset_pwr_list are precisely along the look vector and in azimuth. Each line of the output geom file contains the unit vector components of the look vector and azimuth vector for each point in the clist_RDC file, one line per point. The range offset along the slant range vector can then be expressed as range_offset*LV where LV is the unit look vector and similarly the azimuth offset can be expressed in the ENU basis as azimuth_offset*AZ where AZ is the unit vector in the azimuth direction. Note that the UP component of the azimuth vector has a consistent value of essentially 0. Estimation of the individual offset components in East, North, and Up requires assumptions about the offset field since only 2 measurements are made of the 3 dimensional field. (e.g. offset in the up direction is 0).

A typical processing sequence to measure range and azimuth offsets on a regular grid in the map geometry is described in the GEO Users Guide section 15 and section H.(Measuring range and azimuth offsets on a regular grid in map coordinates).

OPTIONS
The sub-sampling factors in northing and easting determine the offset measurement density when using the output point coordinate lists as input to offset_pwr_clist of ras_clist.