, Volume 15, Issue 4-5, pp 295-307

Particle displacement tracking technique and Cramer-Rao lower bound error in centroid estimates from CCD imagery

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An efficient video based, multi-frame particle displacement tracking technique is presented. The technique is demonstrated on a thermocapillary flow. The Cramer-Rao lower bound centroid measurement uncertainty is derived for Gaussian particle images with Poisson noise recorded on a CCD array. The optimal particle image diameter is determined to be approximately 11/2 pixels. The centroid error increases for particle image diameters larger or smaller than the optimal value. The particle centroid results are carried over to the case of a cross-correlation peak centroid estimate. Particle tracking techniques are shown to have higher accuracy than auto or cross-correlation techniques when the individual velocity measurements are averaged over a comparable correlation subregion.

A version of this paper was presented at the 13th Symposium on Turbulence, University of Missouri-Rolla, Sept. 21–23, 1992.