ANSI-C program: dh_map_orb.c
NAME
dh_map_orb - Calculate
delta height and sensitivity of the interferometric phase with
respect to terrain height from the orbit geometry and
differential interferometric phase
SYNOPSIS
dh_map_orb <SLC1_par> <SLC2R_par>
<OFF_par> <hgt> <dp> <dpdh> <dh>
[SLC_ref_par] [int_mode]
| <SLC1_par> | (input) SLC image parameter file of SLC-1 (reference SLC of interferometric pair) |
| <SLC2R_par> | (input) SLC image parameter file of SLC-2R (resampled SLC of the pair) |
| <OFF_par> | (input) ISP processing/offset parameter file (of interferometric pair) |
| <hgt> | (input) height map in the same geometry as the interferogram (enter - for none) |
| <dp> | (input) interferogram phase - simulated phase (radians) (float, enter - for none) |
| <dpdh> | (output) derivative of interferometric phase with respect to height calculated using state vectors and local height (radians/m) (float, enter - for none) |
| <dh> | (output) height difference calculated from dp using dpdh (m) (float, enter - for none) |
| [SLC_ref_par] |
(input) SLC parameter file
of the image used for geometric co-registration of SLC1 and
SLC2R (enter - for none) |
| [int_mode] |
(input)
interferometric acquisition mode: 0: single-pass mode (Tandem-X) 1: repeat-pass mode (default) |
EXAMPLE
dh_map_orb slc/20120429.TSX_HH.slc.par
slc/20120429.TDX_HH.slc.par
diff0_2d/20120429.TSX_HH_20120429.TDX_HH.off geo/perth_dem.rdc
diff0_2d/20120429.TSX_HH_20120429.TDX_HH.adf.unw
diff0_2d/20120429.TSX_HH_20120429.TDX_HH.dpdh
diff0_2d/20120429.TSX_HH_20120429.TDX_HH.dh
slc/20120429.TSX_HH.slc.par 0
This program calculates a correction in height derived from the differential interferometric phase of a Tandem-X image pair. It also calculates the derivative phase the interferometric phase with respect to terrain height.
DESCRIPTION
When generating a differential interferogram a terrain model resampled in the radar geometry is used to simulate the phase related to terrain. The most accurate way to simulate the phase is to determine the space-craft position for each pass based on the SAR processing parameters and the orbital state vectors. Due to limitations in the input terrain model there is usually a residual phase in the differential interferogram that is related to height error. dh_orb_map estimates the derivative of interferometric phase with respect to height. The interferometric phase is determined using the same approach as phase_sim_orb. The correction to the DEM height dh is equal to the differential interferogram phase dphi divided by the derivative of phase with respect to height: dpdh.
This program is especially useful when there is no differential atmospheric phase as is the case with Tandem-X data. The Tandem-X radar system consists of 2 satellites and simultaneously acquires the images of the interferometric pair. If dh_map_orb is used with repeat-pass interferograms, then the atmospheric interferometric phase will cause errors in dh. It is also possible to calculate a correction to the DEM using a stack of differential interferograms using the program mb in the IPTA package. Since mb uses a stack of interferograms this leads to a reduction in the effect of atmospheric phase on the height correction values.
The user has the option to select either single-pass or repeat-pass mode for the program. For bistatic data, such as Tandem-X, the single-pass mode must be selected. The SLC of the parameter file used for geometric coregistration of the SLC data is required when the reference scene SLC1_par differs from the geometric reference scene.
The sensitivity to height of the interferogram is proportional to the perpendicular component of the baseline. Bperp can be determined using the program base_calc.
In the case where there is no DEM available to calculate the derivative, the derivative is calculated at a mean height of 500 meters.
The height correction dh can be added to the existing DEM using the program float_math. The dh and dpdh data can be displayed using the program disdt_pwr24 and rasdt_pwr24.
SEE
ALSO
phase_sim_orb, mb, base_calc