gpiv(1) Analyzes images obtained from a fluid flow by Particle Image


gpiv [-? | --help] [--usage] [--console_bins BINS] [--console_tooltips] [--console_view_gpivbuttons] [--console_view_tabulator] [--display_background INT] [--display_intregs] [--display_piv] [--display_stretch] [--display_scalar INT] [--display_vectorscale SCALE] [--display_view_menubar] [--display_view_rulers] [--display_zoomscale SCALE] [--hdf] [--img_fmt] [--mpi_nodes] [-p | --print] [--process_imgproc] [--process_piv] [--process_gradient] [--process_resstatst] [--process_errvec] [--process_peaklock] [--process_average] [--process_scale] [--process_substract] [--process_vorstra] [IMAGE1, IMAGE2, ...]


Gpiv is a Graphic User Interface program for recording and analyzing images obtained from a fluid flow that has been seeded with tracer particles by the so-called Particle Image Velocimetry (PIV) technique. It allows to have a quick overview of the process settings, easily changing them, executing the processes, visualizing and optimizing their results in an interactive way. The processes that may be performed are image recording, interrogation (resulting into PIV estimators), validation and post-processing of the PIV estimators.

The settings for the PIV processes are subsequently searched in ~/.gpivrc or in gpiv.conf (system wide), which is provided by libgpiv.

For recording images, gpiv recognizes (CCD) cameras that are IIDC-compliant and connected to the Computer with the IEEE1394 or Firewire protocol.

In case gpiv will trigger a camera and lasers, it uses a kernel module gpivtrig_rtl from the gpivtrig package that depends on the Real Time Application Interface (RTAI) and RealTimeLinux. Trigger pulses are send to the parallel port of the Computer (/dev/lpt0 or /dev/lpt1; see the configure script of the gpivtrig package) at bins #1 (camera), #2 and #3 (first and second laser respectively). The program may be started directly if all modules have been loaded or by the gpiv_control script, also included in the gpivtrig package, which takes care of the loading and unloading of the needed kernel modules. Currently, the trigger system is tested with RTAI-3.1 and the linux kernel-2.4.27.

The parameters and options to be used for gpiv are obtained from ~/.gnome2/gpiv or default settings are to be used if absent. The settings may be changed or updated by menu->settings->preferences. The parameters of gpiv (not the PIV process settings) may be overruled by the command line options, as explained below.

When gpiv is used on a (Beowulf, distributed memory) cluster, the MPI-parallelised program gpiv_rr from the gpivtools package is invoked using mpirun. The gpiv program, however, is launched in the normal way, without invoking mpirun.


-? | --help
On-line help. Besides the options of gpiv it also shows the additional GNOME, GTK and GNOME GUI options.

Display a brief usage message.

--console_bins BINS
Number of bins for histograms of estimators at sub-pixel level, performed by the peaklock process and of the median residues, performed by the errvec process.

-t | --console_tooltips
Show tooltips.

View the gpiv buttons of the application.

View the tabulator of the application containing all PIV process settings.

--display_background INT
Displaying of background: INT = 0: darkblue INT = 1: black INT = 2: first frame of image INT = 3: second frame of image

Enables displaying of interrogation regions.

Displaying of PIV data.

Enables automatic stretching of the display when zooming.

--display_scalar INT
Display derived quantities from PIV data: INT = 0: none INT = 1: vorticity INT = 2: shear strain INT = 3: normal strain

Enables displaying of the menubar.

Enables displaying of the ruler.

--display_vectorscale SCALE
Display vector with index: SCALE = 0: magnification factor = 1, SCALE = 1: magnification factor = 2, SCALE = 2: magnification factor = 4, SCALE = 3: magnification factor = 8, SCALE = 4: magnification factor = 16, SCALE = 5: magnification factor = 32, SCALE = 3: magnification factor = 64, SCALE = 4: magnification factor = 128, SCALE = 5: magnification factor = 256.

-z | --display_zoomscale SCALE
Display zoom with index: SCALE = 0: magnification factor = 0.5, SCALE = 1: magnification factor = 0.83, SCALE = 2: magnification factor = 1.0, SCALE = 3: magnification factor = 1.3, SCALE = 4: magnification factor = 1.6, SCALE = 5: magnification factor = 2.0.

Save data in HDF5 format with .gpi extension.

--img_fmt INT
store (modified) image data and header in: INT = 0: PNG format, INT = 1: raw format, INT = 2: HDF5 format, included with the resulting PIV and post-processing data with .gpi extension.

--mpi_nodes INT
To define the number of nodes when used on a cluster. Used by mpirun -np INT.

-p | --print
Print process parameter settings to stdout.

Includes image processing in the chain-process.

Includes piv interrogation in the chain-process.

Includes testing on the displacement gradient within interrogation area in the chain-process.

Includes calculation of statistics of displacement residuals in the chain-process.

Includes validation on PIV data in the chain-process.

Includes peak lock in the chain- process.

Includes calculation of the whole field average PIV displacements in the chain-process.

Includes scaling in the chain-process.

Includes substracting of the whole field average PIV displacements in the chain-process.

Includes calculation of vorticity in the chain-process.

Loads IMAGE1, IMAGE2, ... from a file or from an URI using the Gnome Virtual File System. The maximum allowed image dimensions and quantity to be loaded are defined by the program as described in gpiv_gui.h or by the 'configure' script during the building of gpiv.


Gerber Van der Graaf