NAME¶
gpivtools - The PIV tool suite.
DESCRIPTION¶
gpivtools is a set of command-line driven programs for the so-called
Digital Particle Image Velocimetry (DPIV). It contains programs for image
recording, processing and analysing (resulting into estimators of particle
displacement, i.e. PIV data), PIV data validation programs and post-processing
tools for manipulating and calculating (scalar) derivatives of the PIV data.
Though the command-line driven tools are mainly intended for non-interactive
processing, its outputs may directly be visualized in a graphical way with the
aid of gnuplot.
The parameters and options to be used for most of the
gpivtools are
provided by Libgpiv. They are subsequently searched in
./gpivrc at
local directory, at
$HOME/.gpivrc (hidden) or at the system-wide
configuration file
gpiv.conf, which is mostly found at
/etc for
UNIX-like operating systems. Each parameter is described by the process key:
GENPAR (general parameters),
CAM (camera settings),
TRIG
(trigger settings),
IMG (image header),
IMGPROC (image
processing),
PIV (piv interrogation),
VALID (piv data
validation) or
POST (piv post processing) and the parameter name,
separated by a dot (.), followed by its value. Some of the parameters are
optional. The parameters may be defined in arbitrary order. Blank lines and
comment (starting with a pound sign (#) at the first column) may be included
in the parameter files. The parameters may be overruled by the command line
options of each tool. Libgpiv provides default parameter values if they are
not defined in one of the configuration files or by an option key at the
command line.
In case stdin and stdout is used, verbose output of the programs is suppressed
in order to avoid contamination of the output data. If
filename is used
for overruling
stdin and
stdout, the parameters are written to
filename.par. By renaming this file to
./gpivrc or
$HOME/.gpivrc, the parameters may directly be re-used for identic
processing of other images and PIV data. The parameters defined in
$HOME/.gpivrc and in
/etc/gpiv.conf are also used by the Graphic
User Interface program
gpiv.
The programs understand different image formats: Portable Network Graphics (
filename .png), HDF5 (
filename.hdf), raw binary
data (
filename.r) that is accompanied by an ASCII header file (
filename.h), and LaVision's (tm) uncompressed image format (
filename .img). Other formats that use lossless compression
(TIF, GIF, PGM, BMP) are converted to PNG on the fly. For interrogation of
double-framed images using cross-correlation, the second image has to be
concatenated after the first one, if this has not already been done by the
recording camera. This might be performed by
gpiv_combing. Image
parameters are read from the header or from the configuration resources
(containing the
IMG key).
Here is the complete list of available
gpivtools programs. See their
individual man pages for a more extended description.
- gpiv_aint
- Calculates mean image intensity at each interrogation area.
This program uses the IMG, PIV and POST parameters.
- gpiv_combing
- Combines two images into one image file for
cross-correlation. This program uses the IMG parameters.
- gpiv_errvec
- Searches the erroneous vectors in a PIV data file and
eventually substitutes them with new values. This program uses the
PIV and POST parameters.
- gpiv_fi-keyline
- Filters each line that starts with a keyword. This program
does not use the parameter resources from Libgpiv.
- gpiv_hdf2piv
- Converts hdf5 PIV data (extension .hdf) to ASCII data. This
program does not use the parameter resources from Libgpiv.
- gpiv_imgproc, gpiv_mktestimg,
gpiv_smooth, gpiv_hilo, gpiv_clip, gpiv_fft,
gpiv_invfft, gpiv_lowpass, gpiv_highpass,
gpiv_getbit, gpiv_mktestimg
- (PIV) image processing programs. These programs use the
IMGPROC parameters.
- gpiv_img2gpiv
- Depreciated: use gpiv_combing instead. Converts
images into raw data (extension .r) format with the belonging ASCII
header (extension .h) or into hdf format (with extension
.hdf). This program does not use the parameter resources from
Libgpiv.
- gpiv_manipiv, gpiv_fasty, gpiv_flipx,
gpiv_flipy, gpiv_revert, gpiv_rot90,
gpiv_rot180
- Simple data manipulation tool for PIV data. These programs
use the POST parameters.
- 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. This program uses the VALID parameters.
- gpiv_piv2gnuplt
- Converts PIV data gnuplot data. Besides this, image
interrogation and post-processing programs are able to display their
results directly (mostly with the -g option). This program does not
use the parameter resources from Libgpiv.
- gpiv_piv2grid
- Converts PIV data to grid data for generating contour plots
with Plotmtv. This program does not use the parameter resources from
Libgpiv.
- gpiv_piv2hdf
- Converts ASCII PIV data to hdf5 formatted data (extension
.hdf). This program does not use the parameter resources from
Libgpiv.
- gpiv_piv2vec
- Adds header to PIV data for a vector plot with Plotmtv.
This program does not use the parameter resources from Libgpiv.
- gpiv_process-chain
- Processes a pipeline of Gpiv-tool command's, forming
process a chain from image recording, image processing, image
interrogation, data validation, data post-processing. This program does
not use the parameter resources from Libgpiv.
- gpiv_recimg
- captures images from a IIDC-compliant CCD camera with
IEE1394 connection. This program uses the IMG parameters.
- gpiv_rr
- Interrogates images in order to obtain displacement
estimators of particles for (Digital) Particle Image Velocimetry. This
program uses the PIV and VALID parameters.
- gpiv_sca2gri
- Converts scalar data from gpiv to grid data for contour
plotting with Plotmtv This program does not use the parameter resources
from Libgpiv.
- gpiv_scale
- Spatial and time scaling program for PIV data. This program
uses the IMG and POST parameters.
- gpiv_series
- Script for (parallel) processing a series of numbered
files. This program does not use the parameter resources from Libgpiv.
- gpiv_suta
- Subtracts time-avaraged velocities (local mean) from the
PIV estimators. This program does not use the parameter resources from
Libgpiv.
- gpiv_s-avg
- Spatial statistics of PIV data. This program uses the
POST parameters.
- gpiv_t-avg
- Calculates time-avaraged mean and rms from a series of PIV
data. This program does not use the parameter resources from Libgpiv.
- gpiv_t-avg-img
- Calculates time-averaged values from a series of images at
each pixel. This program uses the GENPAR parameters.
- gpiv_t-corr
- Calculates the velocity correlation as function of time
(Eulerian correlation) from a series PIV data sets This program does not
use the parameter resources from Libgpiv.
- gpiv_trig
- Triggers a (double Nd_YAGG) laser on a CCD camera. This
program uses the TRIG parameters.
- gpiv_uhisto
- Tests PIV data by printing/displaying an histogram of the
horizontal particle displacements. This program uses the VALID
parameters.
- gpiv_vhisto
- Tests PIV data by printing/displaying an histogram of the
vertical particle displacements. This program uses the VALID
parameters.
- gpiv_vorstra, gpiv_vorty,
gpiv_nstrain, gpiv_sstrain
- Calculates the differential quantities vorticity, shear
strain and normal strain from PIV data. These programs use the POST
parameters.
SEE ALSO¶
gpiv, gpiv_control
AUTHOR¶
Gerber Van der Graaf