Ellipse-fitting techniques applied to 2D-PMS raindrop images

Abstract

An ellipse-fitting technique is introduced in this paper to process the images of raindrops sampled by a 2D-PMS (Particle Measuring Systems, Inc.) probe. Algorithms to estimate size, shape, and orientation parameters of partial raindrop images are presented. This technique is evaluated by fitting full raindrop images and comparing the results with other procedures such as Fourier descriptor and moment descriptor methods. It is also evaluated by applying this procedure to partial raindrop images constructed by truncating the top part or the bottom part of full raindrop images, while at the same time the estimates obtained from the full images are used for comparison against the estimates from partial images. It is shown that the ellipse-fitting technique is a viable tool for processing complete 20-PMS raindrop images, and more importantly, this technique works successfully for processing partial raindrop images. Results of 20-PMS data analysis of side-looking raindrop images collected during the CaPE (Convection and Precipitation/Electrification) field program are presented.