Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

gpiv_scale(1) [debian man page]

GPIV_SCALE(1)						      General Commands Manual						     GPIV_SCALE(1)

NAME
gpiv_scale - Scaling of PIV data. SYNOPSIS
gpiv_scale [-h | --help] [-p | --print] [-s M |-S M] [-t dT |-T dT] [-v | --version] [-zp x0 y0] [-zv x0 y0] [filename] < stdin > stdout DESCRIPTION
gpiv_scale applies the image magnification and the time between successive recordings to the PIV estimators. This results that particle displacements [px] are modified to velocities [m/s] and their positions from [px] to [m]. A physical reference for the positions of the PIV data can be applied by means of the image zero-offset option. If filename is used, the parameters and options to be used for gpiv_scale are subsequently read from the image header (filename.h in case of raw binary images) or from the configuration resources (containing the IMG and POST keys). The parameters may be overruled by the com- mand line options, as explained below. Options -h | --help On-line help. -p | --print Prints parameters, command line options and input and output filenames to stdout. The output is identic of filename.par, in case -f is used. -s M spatial scaling with magnification factor M [m/px] -S M Inverse spatial scaling with magnification factor M [m/px]; returns scaled data to their original magnitudes. -v | --version Prints version information on standard output, then exits successfully. -t dT Translates particle displacements into velocities by devising them with the time between subsequent recordings dT [s]. -T dT Inverse time scaling. Returns velocities into displacements [px] [-z x0 y0] Relates the positions of the observations of velocities/displacements to a physical location in the experiment by image zero offset- ting. x0 y0 denote the physical position of pixel (0,0) in the image. filename Input PIV file. Overrides stdin and stdout. The output will be written to filename.sc.piv. Parameters are stored in filename.par and may be used for future use by including them in ./gpivrc. SEE ALSO gpivtools NOTES
AUTHOR
Gerber Van der Graaf BUGS
The program has been tested for PIV data. So far, no bugs have been found. 8 November 2006 GPIV_SCALE(1)

Check Out this Related Man Page

GPIV_ERRVEC(1)						      General Commands Manual						    GPIV_ERRVEC(1)

NAME
gpiv_errvec - Searches erroneous vectors in a PIV data file and substitutes with new values. SYNOPSIS
gpiv_errvec [-a] [-b ] [-g][-h] [-h | --help] [-i | --image_type S] [-n N] [--no_b ] [-p | --print] [-r N] [-s N] [-t F] [-u | --surround] [-v | --version] [filename] < stdin > stdout DESCRIPTION
gpiv_errvec searches erroneous outliers in a PIV data stream and substitutes with new values, if possible, i.e. if (the majority) of its surroundings are non-erroneous. Evaluation of erroneous vectors is done by looking up the Signal to Noise Ratio (SNR) value in the PIV data file or by calculating the median residu of the vector with its surroundings. A new displacement is obtained by the mean value of the surrounding values or by the location of the next higher peak in the covariance function. PIV data validation is not needed anymore while this is now done during image interrogation with gpiv_rr. Though using gpiv_errvec will not harm. The configuration parameters (containing the VALID key) may be overruled by the command line options, as explained below. Options -a Automatic threshold; calculates threshold value from residu histogram. -b Calculate statistics of the median residues and print a histogram of N bins. -g Graphical visualization of residu statistics with gnuplot (needs filename). -b is not required as this option will be set automati- cally. -h | --help On-line help. -i | --image_type S Image type or format to be used if particle displacements will have to be re-estimated at the next highest correlation peak. S may be png, tif, gif, bmp, pgm, r or gpi. Default: png. -n N Defines number of histogram of bins N for -b or -a --no_b N suppresses printing median residu histogram -p | --print Print parameters, command line options and eventually used input and output filenames to stdout. The output is identic of file- name.par, in case filename is used. -r N Erroneous vector determined by SNR of the correlation function (N = 0), median residu (N = 1) or normalized median (N = 2), i.e. the ratio between median residu with current datapoint included and between median residu of surroundigs (with datapoint excluded). -s N Substitution of the erroneous vectors by (N = 0) nothing, the local mean from the surrounding values (N = 1), median (N = 2) or next highest covariance peak (N = 3, needs filename). -t F Threshold value F of SNR or median residu to determine validity of particle displacement. -u | --surround Odd number representing the surrounding grid points to be used for local mean and median values. -v | --version Print version information on standard output, then exit successfully. filename Full name of PIV data file for input. Substitutes stdin and stdout. Output will be written to filename.erv.piv. The parameters will be written or appended to filename.par and may be used for future use by including them in ./gpivrc. If particle displacements will have to be re-estimated at the next highest correlation peak, filename is required. SEE ALSO
gpivtools AUTHOR
Gerber Van der Graaf BUGS
The program has been tested for artificial generated DPIV images. So far, no serious bugs have been found. 23 May 2005 GPIV_ERRVEC(1)
Man Page

Featured Tech Videos