ANSI-C program: cct_pt.c
NAME
cct_pt - spatial filter and reference point bias removal for
point data (single record or all records)
SYNOPSIS
cct_pt <plist> <pmask> <SLC_par>
<pdata_in> <pcct> [type] [r_max] [w_func]
[np_min]
| <plist> | (input) point list (int) |
| <pmask> | (input) point data stack of mask values (uchar, set to - to accept all points) |
| <SLC_par> | (input) SLC parameter file of point list coordinates |
| <pint> | (input) point data stack (float or fcomplex) |
| <pccs> | (output) spatial interferometric correlation
estimate |
| [type] | data type (0:fcomplex 2:float, default -: fcomplex) |
| [r_max] | maximum radius used to search for points(range samples, default: 8) |
| [w_func] | radial weighting function used to determine local average (0: 1.0 default=1: 1.0-radius/r_max) |
| [np_min] | minimum number of points in the corelation estimate
(default = 5) |
EXAMPLE
cct_pt pt pmask0 08256.rslc.par pdiff2 pccs2 0
8
Source code cct_pt.c in ./IPTA/src, executable version cct_pt in ./IPTA/bin
DESCRIPTION
cct_pt estimates the
temporal phase coherence of point data stacks. Data can either be
in fcomplex or float format. If in float format it is assumed
that the data are
unwrapped phase and are converted to complex unit vectors
where re = cos(phase), imagi = sin(phase). For fcomplex data the
values are normalized to unit magnitude. The correlation
estimate
is the magnitude of the sum of the point interferogram values
through the stack divided by the number of points and varies
between 0, and 1.0.
In order to compare the values between the stack layers, the local average phase of each layer is subtracted from that layer. The local average is determined from a weighted average of points within a specified radius of the point. The user can specify the radial diameter (nominally 8) of the search region to evalutate the local average If insufficient points are found, the correlation value for that point is set to 0. The command line parameter np_min sets the minimum number of points within the search region required to return a correlation estimate. The local average is a weighted sum using either a constant or triangular weighting function. (set via the w_func command line parameter).
OPTIONS
none.
SEE ALSO
© Copyrights for Documentation, Users Guide and Reference Manual by Gamma Remote Sensing, 2003.
UW, CW,TS,
last change 16-Aug-2004.