Sizing of particles and droplets using 3D-PTV, an OpenPTV post-processing tool

A methodology to obtain particle sizes from images was created, this tool can be used as a post-processing tool to the open source software OpenPTV. The proposed methodology uses the same images and information obtained during the 3D calibration of OpenPTV to estimate the real sizes of the observed particles. The objective of this paper is to introduce the followed methodology to create a sizing tool and validate the technique with different solid particles and water droplets. The method requires an extra calibration with a flat target containing circles of different sizes, but if the calibration is successful, the sizes of particles can be estimated reliably with a maximum relative error of 10%, as long as the particle diameter correspond to at least three pixels width in the obtained images.