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# Introduction

## 1.1 General description

Gpiv (Figure 1.1) is a program to record and interrogating images for Particle Image Velocimetry (PIV). It also includes algorithms for validation of the PIV estimators and post-processing that result into derived (scalar) flow quantities. It gives an overview of the parameters in a logical and organized way, allows to run the processes individually or in a pipeline process and visualizes the results. Gpiv displays the images, interrogation area's, piv estimators, outliers, excessive velocity gradients and post processing results in a single window frame. The resulting estimator values may be displayed interactively. The graphical user interface of Gpiv has been written with the GTK/GNOME libraries.

Gpiv is one of the end-user programs that makes extensively use of Libgpiv. Libgpiv includes the main algorithms for interrogation, validation, post-processing, memory (de)allocation, in-and output handling, etc. Other end-user programs may be found in the Gpivtools package. Gpivtools contains command line programs that may be invoked from a shell or from scripts. Some PERL scripts are found in the Gpivtools package, as well. All codes have been written in ANSI-C and have been developed on a LINUX box.

Figure 1.1 Screenshot of Gpiv with PIV estimators (vectors) from an artificial, computer generated image pair [1] and the derived vorticity field (background color)

## 1.2 License

Gpiv is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

## 1.3 Final remarks

I kindly ask to acknowledge the use of the software in articles, reports etc. in case the software has considerably contributed to the work presented. I hope you'll enjoy Gpiv. Suggestions for improvements and additions are welcome.

Gerber van der Graaf
e-mail: gerber_graaf@users.sourceforge.net

## References

[1] Okamoto, K., Nishio, S., Saga, T. and Kobayashi, T., 2000, "Standard images for particle-image velocimetry," Meas. Sci. Technol., 11, 685-691. vsj.or.jp/piv/

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