gpiv_peaklck(1) Tests PIV data on the so-called peak-locking effect


gpiv_peaklck [-g] [-h | --help] [-n N] [-p | --print] [-v | --version] [filename] < stdin > stdout


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.


-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.

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.


Gerber Van der Graaf


The program seems to work fine with real PIV data. So far, no serious bugs have been found.