ANSI-C program: phase_slope.c
NAME
phase_slope - Calculate phase slope in range and azimuth.
SYNOPSIS
phase_slope <interf> <slopes> <width>
[win_sz] [thres] [xmin] [xmax] [ymin] [ymax]
| <interf> | (input) interferogram (fcomplex) |
| <slopes> | (output) range and azimuth phase slopes (fcomplex) |
| <width> | number of samples/row |
| [win_sz] | size of region used for slopes determination (default = 5) |
| [thres] | correlation threshold for accepting slope estimates 0.0 -> 1.0 (default=.4) |
| [xmin] | starting range pixel offset (default = 0) |
| [xmax] | last range pixel offset (default = width-1) |
| [ymin] | starting azimuth row offset (default = 0) |
| [ymax] | last azimuth row offset (default = width-1) |
EXAMPLE
phase_slope 1352_1610.flt 1352_1610.slopes 2500
5
Estimates phase slopes of input interferogram in range and azimuth direction
DESCRIPTION
phase_slope reads the complex valued input interferogram
(fcomplex format is required) and determines the phase slopes in
range and azimuth direction. The phase slopes in range and
azimuth direction are written out to the slopes file which is in
fcomplex format with the real parts corresponding to the range
phase slopes and the imaginary parts to the azimuth phase
slopes.
For the slope estimation a window of the indicated size is used. In addition to the slope values a correlation value is determined as a measure for the reliability of the slope estimate. Slope estimates with a low reliability (below the indicated threshold) are replaced by the NULL value (0.0,0.0).
Filtering of the input interferogram prior to the slope estimation is recommended to reduce the phase noise. timation bias cannot be avoided.
The main use of the slope files generated by phase_slope is to support the adaptive coherence estimation with the program cc_ad. Based on the estimated slopes cc_ad removes the local phase trend which results in an improved estimation with higher coherence values in tilted terrain. thresholding is recommended to avoid introduction of artifacts in areas of high phase noise respectively low coherence.
SEE ALSO
typedef_ISP.h, cc_ad