FOLKI-SPIV Fast and accurate PIV vector processing based on GPU
FOLKI-SPIV is a PIV vector field computation software recently developed by the ALPIV team, and presently at use in several departments of ONERA. It is based on the FOLKI (French acronym for Iterative Lucas-Kanade Optical Flow) algorithmic core, which was firstly introduced in the field of computer vision [1]. Starting from this core, various additional modules useful to PIV and to Stereo PIV have been integrated to lead to the complete FOLKI-SPIV solution [2]. The present version gathers a large range of everyday use pre-processing, processing and post-processing tools, among which:
Local mean and standard deviation of the image intensities
Possibility of subtracting (or dividing by) an average image
Mask handling
Square or rectangular interrogation windows, with top-hat or gaussian weighting
Bilinear or third order B-spline interpolator
Stereo vector field computation using a direct one-step approach, avoiding the stereo reconstruction step [3]
Self-calibration for Stereo PIV
Integrated macro language, for automatic processing of large datasets
The animation below shows a live processing of 50 image pairs from a high-speed PIV campaign in the S19Ch wind-tunnel (massive separation over a rounded ramp). Macro files are used to, firstly, load a mask and the computation parameters, and then, to load and compute the image pairs. In between, the demo shows some of the display features (enhancement, zoom) of FOLKI-SPIV. Processed on a desktop computer equipped with an NVIDIA Tesla C2050 GPU.
A demo version of FOLKI-SPIV for Windows (XP, 7) is available here.
Video screen capture of a FOLKI-SPIV demo. Processing of 50 image pairs of 2D2C PIV images of flow separation over a rounded ramp (S19Ch wind-tunnel).
See also other applications based on the FOLKI algorithmic core and implemented on GPU on DTIM's gpu for image webpage.
References
[1] Le Besnerais G., Champagnat F., Dense optical flow estimation by iterative local window registration, in Proceedings of IEEE ICIP05, vol. 1, pp. , Genova, Italy, Sept. 2005.
[2] Champagnat F., Plyer A., Le Besnerais G., Leclaire B., Davoust S., Le Sant Y., Fast and accurate PIV computation using highly parallel iterative correlation maximization, Exp. Fluids 50(4), 1169-1182, 2011.
[3] Leclaire B., Jaubert B., Champagnat F., Le Besnerais G., Le Sant Y., FOLKI-3C: a simple, fast and direct algorithm for Stereo PIV, in Proceedings of the 8th International Symposium on Particle Image Velocimetry - PIV09, Melbourne, Australia, Aug. 2009.
