Parametric study on light field volumetric particle image velocimetry

Abstract

This paper presents a comprehensive investigation on how key design features can affect the performance of a plenoptic camera for single-camera volumetric velocity measurement technique. It firstly presents the prototyping of an in-house high resolution plenoptic camera; followed by an introduction to the framework of reconstructing 3D particle images from 2D light field images. Based on linear optics, a set of synthetic light field images were then generated by tracing light rays from a point light source to the plenoptic camera sensor. Detailed analysis were performed on these images to examine the effects of key parameters such as pixel microlens ratio (PMR), microlens geometry, reconstruction iteration number, relaxation factor and voxel to pixel ratio on the resolution of plenoptic camera and the final particle reconstruction quality. It is found that the microlens geometry is the vital parameter that affects the overall system performance. Hexagonal microlens generally outperforms square microlens in terms of resolution and reconstruction quality. Another important parameter is PMR, which affects resolution in x-, y- and z-directions, and high PMR does not necessarily lead to a better reconstruction quality.