PIV News
Version 0.5.0
Libgpiv 0.5 has been released: we are now halfway stable and production release. At least concerning version numbering. Hopefully that the needed time for developing the second half will take less :)- Libgpiv has undergone a Kafka revision: simplification, reduction and a more uniform library interface (API). In the hope that it will be easier to learn Libgpiv for developing your own applications and for wrapping the library to other languages.
- New structure for images. Structures for PIV data and scalar data have been improved and extended.
- Many functions have been revised and some memory leaks have been disabled.
- The fftw3 library is used now for performing FT operations.
- Documentation of the API, generated with Doxygen, is included in the package and can also be found on this site.
- Of course, Gpivtools and Gpiv have been adapted to the new Libgpiv API.
Thanks to the API revision a new project has been launched: PyGpiv which is a Python module that allows the functionality of Libgpiv in Python scripts.
The Gpiv program now includes the Gnome Virtual File System (GVFS): images and data may be retrieved or stored from / to an URI. This allows to load data directly from a (ftp. ssh, ...) server or by drag and drop of the Gnome Filemanager (Nautilus), that is connected to such a server.
For more detailed information, have a look at the Changelogs of the individual packages.
Version 0.4.0
- Extension with the loading and saving of (gray-type) images of the following formats: PNG (native), GIF, TIF, BPM, PGM. Apart from these formats, the software also loads raw binary (.r/.h), hdf5 (.gpi) and LaVision's (tm) uncompressed (.img) images.
- The image dimension parameters in the Gpiv program have been removed. Gpiv may load images of arbitrary dimensions, even mixed during a single session.
- Image loading while launching Gpiv from the command line.
- Improvement of the viewer display of Gpiv:
- zooming with mouse wheel and dragging with mouse pointer
- non-interlaced displaying of images and data
- added a menubar (with identic functionality of the popup menu)
- added rulers to show pointer position. patch1:
- added automatic stretching of buffer display
- broadcast changed display settings from 'preferences' to all buffers
- In Gpiv's console PIV tab: Monitor of interrogation area's, correlation function and displacement vector with non-interlaced canvas.
- Added Gauss weighting of interrogation area's to reduce ripple effects caused by the abrupt intensity changes at its borders.
- Added Symmetric Phase Only Filtering (SPOF) on correlation function [3].
Version 0.3.1
Minor changes that include the bug repair patches from 0.3.0 in order to get the software accepted in the Debian GNU/Linux distribution.patch3: added support for png (native) tif, gif, pgm and bmp image formats
Version 0.3.0-b
The gpiv-0.3.0 package that has been published at the sourforge sites includes version 0.3.0-b and 0.3.0-a.- Advanced interrogation technique by applying image deformation. This reduces drasticly peaklocking effects resulting into higher spatial resolution and accuracy.
- Cumulative residus (representing the sum of differences between PIV estimators of the current and the previous iteration) used as convergence criterium for iterative interrogation procedures.
- PIV data validation after each iteration step.
- Normalized (local median) residus can be used as a universal outlier detection in a PIV estimation for (heterogeneous) turbulent flows [1].
Version 0.3.0-a
The revision with the modifications mentioned below has been distributed on a Linux live CD (based on Morphix, Knoppix and GNU/Debian) during the 6th Int. Symp. on Particle Image Velocimetry, Sept 2005, Caltech, Pasadena, USA and has been applied during the PIV Challenge 05 project.- The adaptive grid system uses bilinear interpolation with shifted knots to increase accuracy of intermediate results [2]. This results into improved estimators at the new, refined, sub-grid and, therefore, into stability of the iteration procedure.
- The interface has been ported to the Gnome2 libraries. The porting has not been finished, yet. This may involve that some functionality has temporarly been lost.
- Several optimizations and internal improvements.
Version 0.2.1
- The software has been extended with Data Acquision (DAC), i.e. the triggering of lasers with a camera and the recording of PIV images from an experiment.
- Adaptive grid if zero offsetting and adaptive dimensions of the Interrogation Area's (I.A) are used. The initial grid of an iterative interrogation uses the dimensions of the largest I.A.'s, as defined by the process parameter, while the area's have an overlap of 50 %. After each iteration sweep (which includes the interrogation of the entire Area of Interest within the image on a rectangular grid), the sizes and adjacent shifts of I.A.'s are halved. Estimators at the new, finer, grid are calculated by (bi)-linear interpolation. This process continues until the final (minimum) dimensions and shifts have been reached.