Feature correlation for particle image velocimetry: An application of pattern recognition

Conference · Sat Dec 30 23:00:00 EST 1995

OSTI ID:220726

Zhang, X; Cox, C S ^[1]

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1. Univ. of California, San Diego, La Jolla, CA (United States). Scripps Institution of Oceanography

Particle Image Velocimetry (PIV) has been used successfully for measuring instantaneous two dimensional velocity fields. Analyzing PIV images involves matching particle images captured sequentially. A feature-recognition method is proposed here for analyzing PIV images. It first extracts structural features of the particle pattern after their locations have been isolated from images. A preliminary process is to replace the particle images by the Cartesian coordinates of particle centers. In this way the brightness of particle images plays no further part, and the point positions are used to establish structural features: topological relations between each point and its neighbors. The interrogation area is defined by a limited number of neighboring points. The size and shape of each interrogation area varies with the distribution of neighbors. A fit to motion, rotation and distortion among the neighbors is then carried out in the space of topological relations of successive images. In this way changes of structural features define fluid spatial translation, rotation, and deformations within each interrogation region. Measurement of feature space in two successive images demands knowledge of the locations of corresponding points derived from individual particles in the two images. Classification of point correspondences, despite confusingly discordant displacements from one image to the next, can be made by taking advantage of physical limitations on the possible movement of particles between the two images. It is found that feature space search and correlation is a much more efficient procedure than correlation operations in the two dimensional image domain.

• OSTI ID: 220726
• Report Number(s): CONF-950793--; ISBN 0-8194-1905-2
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
ALGORITHMS
DATA ANALYSIS
DIAGNOSTIC TECHNIQUES
FLOW VISUALIZATION
FLUID FLOW
MEASURING METHODS
OPTICAL SYSTEMS
VELOCIMETERS
VELOCITY