Three-Dimensional Particle Image Velocimetry Using a Plenoptic Camera

A novel 3-D, 3-C PIV technique is described, based on volume illumination and a plenoptic camera to measure a velocity field. The technique is based on plenoptic photography, which uses a dense microlens array mounted near a camera sensor to sample the spatial and angular distribution of light entering the camera. Various algorithms are then used to reconstruct a volumetric intensity field after the image is taken, and cross-correlation algorithms extract the velocity field from the reconstructed volume. This paper provides an introduction to the concepts of light fields and plenoptic photography, and describes the algorithms used to reconstruct the measurement volume. A comparison is made between the use of a combined computational refocusing and thresholding approach versus a direct tomographic reconstruction approach. This discussion lays the groundwork for a more detailed study of reconstruction accuracy, achieveable particle number density, reconstruction ambiguities (e.g., ghost particles), and other factors in a following study. Additionally, the construction of a prototype camera based on a 16-megapixel interline CCD sensor is described and preliminary experimental renderings are given.