Gamma DIFF&GEO: Reference Manual

dispmap_vec

NAME
dispmap_vec - Calculation of displacement vector field from displacement direction and measured component.

SYNOPSIS
dispmap_vec <DEM_par> <dispmap> <lv_theta> <lv_phi> <fv_theta> <fv_phi> <dv_norm> [dv_theta] [dv_phi] [dv_x] [dv_y] [dv_z]

<DEM_par>	(input) DEM/MAP parameter file
<dispmap>	(input) displacement observation (along look-vector) (file of float)
<lv_theta>	(input) look-vector elevation angle (file of float or constant value in deg.)
<lv_phi>	(input) look-vector orientation angle (file of float or constant value in deg.)
<fv_theta>	(input) flow-vector elevation angle (file of float or constant value in deg.)
<fv_phi>	(input) flow-vector orientation angle (file of float or constant value in deg.)
<dv_norm>	(output) norm of 3-dim displacement vector (file of float)
[dv_theta]	(output) elevation angle of 3-dim displacement vector (file of float)
[dv_phi]	(output) orientation angle of 3-dim displacement vector (file of float)
[dv_x]	(output) easting component of 3-dim displacement vector (file of float)
[dv_y]	(output) northing component of 3-dim displacement vector (file of float)
[dv_z]	(output) vertical component of 3-dim displacement vector (file of float)
[mask_angle]	cutoff angle in degrees between the look and normal vector to mask inaccurate results (default=5)

EXAMPLE
dispmap_vec aoi.dem_par aoi.disp aoi.lv_theta aoi.lv_phi aoi.grad_theta aoi.grad_phi aoi.disp_norm aoi.disp_theta aoi.disp_phi

Calculates the 3D displacement field based on the indicated DINSAR based line-of-sight displacement component and the indicated direction field (along height gradient). The output displacement field is expressed through the norm, the elevation angle (theta) and the orientation angle (phi).

dispmap_vec aoi.dem_par aoi.disp aoi.lv_theta aoi.lv_phi aoi.grad_theta aoi.grad_phi aoi.disp_norm - - aoi.disp_x aoi.disp_y aoi.disp_z

Calculates the 3D displacement field based on the indicated DINSAR based line-of-sight displacement component and the indicated direction field (along height gradient). The output displacement field is expressed through the easting (x), northing (y) and vertical (z) components.

DESCRIPTION
dispmap_vec calculates the displacement vector field based on the indicated DINSAR based component and displacement direction field. The main application is in landslides and glacier motion monitoring where the assumption of motion along the gradient of the topograpic height is an often used assumption. The program permits to calculate the 3D displacement vector field from the DINSAR result (which provides only the displacement component in the direction of the SAR look vector and the displacement direction field (derived e.g. using the assumption of flow along the height gradient).

The dimensions of the image files and the map projection which is the reference are defined in the DEM/map parameter file.

Differential interferometry permits to estimate the deformation component in the SAR look direction. This DINSAR based information is specified through the displacement component in the look direction and the direction angles (elevation theta and orientation phi) in the map geometry. The look vector direction angles can be determined using the program look_vector.

The motion or flow direction is indicated through the related direction angles (elevation theta and orientation phi). For the case of motion along the surface height gradient the flow direction field can be calculated based on a DEM using the program dem_gradient.

The output displacement vector is available as displacement norm, elevation and orientation angles, or as easting (x), northing (y) and vertical (up) components, stored in separate binary files (float).

Notice that the displacement vector components (norm, elevation and orientation angle) will differ from the indicated flow direction field because for "negative" displacements along the indicated direction (different sign of vector).

The elevation angle is defined as the angle between the horizontal surface and the look vector with positive angles indicating sensor positions above the surface. The orientation angle is defined as the angle between the East direction and the projection of the look vector on the horizontal surface plan. The orientation angle increases towards north, with the North direction corresponding to PI/2 (and south to -PI/2). Both angles are expressed in radian.

Warning: the interferometric observation is only sensitive to motion in the SAR look vector direction. For other directions the sensitivity is reduced which will lead to higher errors.

OPTIONS
Other flow direction fields (than the DEM gradient field) calculated from geophysical (or geometrical models) can be used. Nevertheless, no specific programs are currently included to calculate the related direction fields.