NAME¶
gpiv_peaklck - Tests PIV data on the so-called peak-locking effect by
printing/displaying an histogram of the particle displacements at sub-pixel
level.
SYNOPSIS¶
gpiv_peaklck [
-g] [
-h |
--help] [
-n
N] [
-p |
--print] [
-v |
--version] [
filename] <
stdin >
stdout
DESCRIPTION¶
Peak-locking effects in Particle Image Velocimetry (PIV) result into estimations
of the particle displacements that are mainly at an integer number of pixels,
instead of at sub-pixel displacements. This effect may due to stretching of
the (round) pixel images, due to a too low resolution of the pixel-image or
may be due to signal interferences of the data from camera to frame grabber.
Gpiv_Peaklck calculates the particle displacement distribution at
sub-pixel level in between 0.0 an 1.0 (0 included, 1 excluded). If peak
locking occurs, a non-uniform distribution of the estimated particle
displacements at sub-pixel level will be found.
The configuration parameters (containing the
VALID key) may be overruled
by the command line options, as explained below.
Options¶
-
-g
- Graphical visualization of the histogram with gnuplot.
- -h | --help
- On-line help
- -n N
- Override number of bins (default 10, hard coded).
- -p | --print
- Print parameters, command line options and eventually used
input and output filenames to stdout. The output is identic of
filename .par, in case -f is used.
- -v | --version
- Print version information on standard output, then exit
successfully.
- filename
- Input PIV data file. Overrides stdin and stdout. Output
will be written to filename.plk. The parameters will be
written or appended to filename.par and may be used for
future use by including them in ./gpivrc.
SEE ALSO¶
gpivtools
AUTHOR¶
Gerber Van der Graaf
BUGS¶
The program seems to work fine with real PIV data. So far, no serious bugs have
been found.