ANSI-C program: dispmap_pt.c
NAME
dispmap_pt - Surface displacement map generation from unwrapped
differential phase.
SYNOPSIS
dispmap_pt <plist> <pmask> <pSLC_par>
<itab> <punw> <phgt> <pdisp>
[mode]
| <plist> | (input) point list (int) |
| <pmaks> | (input) point data stack of mask values (uchar, set to - to accept all points) |
| <pSLC_par> | (input) stack of SLC/MLI parameters (binary) |
| <itab> | (input) table associating interferogram stack records
with pairs of SLC stack records (ascii) (line entries are: pSLC_rec1 pSLC_rec2 itab_rec_num switch_flag) |
| <punw> | (input) point data stack of unwrapped interferometric phases for each point and each layer in the stack (float) |
| <phgt> | (input) point data stack of terrain heights (float) (enter - for none) |
| <pdisp> | (output) displacement (m) for each point and each layer in the stack (binary) |
| <mode> | displacement calculation mode: 0: along look vector (LOS), +: towards sensor (m) (default) 1: vertical displacement, +: increasing height (m) 2: horizontal displacement, +: decreasing ground range (m) |
EXAMPLE
dispmap_pt pt_5 pmsk1 pSLC_par itab punw1 phgt pdisp1
1
Converts the unwrapped differential interferometric phase in
stack punw1 to a vertical displacement (subsidence) map.
The point list is pt_5 and the point mask is pmsk1
DESCRIPTION
dispmap_pt converts the
point unwrapped differential interferometric phase into a surface
deformation map in meters. The differential interferometric phase
is proportional to the displacement along the SAR look vector. As
a consequence the 3-dimensional displacement of a surface element
cannot be completely described. Under the assumption of a
predefined surface displacement direction conversion to vertical
or horizontal displacements is possible. The geometrical
reference is chosen to be reference SLC of the first
interferogram listed in the itab file. The itab contains
information on the SLCs used to generate the individual
differential interferograms.
To convert the unwrapped phase to displacement along the look vector in meters with positive signs corresponding to displacement towards the sensor dispmap_pt mode 0 is selected. For this conversion no specific assumption on the surface deformation is necessary. To map vertical displacement in meters with positive signs corresponding to increasing surface height and negative signs to subsidence, dispmap_pt mode 1 is selected. Vertical displacement can often be assumed in the case of subsidence.
To map the horizontal displacement component in the ground
range direction in meters with a positive sign
corresponding to decreasing ground range, dispmap_pt mode 2 is
selected.
Note that the mapping of displacement along the terrain surface,
as required in the mapping of glacier velocity, is not supported
by dispmap_pt.
OPTIONS
Terrain heights are required for the conversion of the unwrapped
phase to the displacement vectors. As an option the height point
data does not need to be entered and a surface reference height
0f 0.0 m is used for the conversion. The effect of the terrain
height on the result may in many cases be neglected in comparison
to other error sources.
SEE ALSO
ipta.h.