CIVx, a free code for image velocimetry
CIVx (Correlation Imaging Velocimetry) is a free advanced Imaging Velocimetry implementation of Direct-Cross Correlation PIV that relies on generalized pattern matching by direct cross-correlation of pattern boxes between image pairs. The source code, written in Fortran, can be downloaded from source forge. CIVx is portable to most computer architectures and operating systems. The binary executable files, compiled for several systems (Linux, win32, MacOS) can be downloaded with the package uvmat.
The Matlab interface uvmat has been developed to run this code, analyse data and perform image preprocessing and geometric calibration.
The following documents provide introduction to PIV techniques used in our Coriolis facility.
Note that although the general principles remain valid, references to software are outdated, see the uvmat online help for updates.
Key features of CIVx:
Spatial decoupling of the pattern box in image a
from its counterpart in image b
Arbitrary grid definition by user or mesh generator
Advanced mask implementation
Correlation multiplication to reduce spurious vectors
Iterative CIV, taking into account pattern deformation by strain and rotation.
Adaptative continuous window shifting to reduce peak-locking effect
Numerical computation can be used as first guess
Standard file format for easy integration with third party solutions.
User defined criterions for false vector removal
Graphical User Interface for automatic distribution of large number of jobs over a network of workstations.
Fincham, A., and G. Spedding, 1997, Low cost, high resolution DPIV for measurement of turbulent fluid flow. Exp. Fluids, 23, 449-462 defined the CIV techniques and several acquisition optimizations.
Fincham A. and Delerce G. (2000) , Advanced optimization of correlation imaging velocimetry algorithms, Experiments in Fluids 29, S13-S22. describe the latest improvements around a hierarchical scheme and images spatial transformations.
Links for PIV software
mpiv: Matlab toolbox for educational and research purpose. The developers’ intention is to keep the codes short and simple.
PIVlab: another simple Matlab toolbox for PIV.
OpenPIV: successor of URAPIV, is an initiative to develop open source software for PIV, using Matlab, Python and C++ executables.
pivmat: Matlab toolbox for post-processing PIV data and turbulence analysis
pivchallenge: reference images for testing PIV software