A Comparison of Plenoptic Imaging System and Camera Array System
The imaging method based on light field data is a hot research topic at present. By recording the location and direction of light, light field imaging can reconstruct the three-dimensional scene. From the point of view of recording method, there are two similar light field recording systems, so-called camera array system and plenoptic imaging system. In order to process data flexibly, the light field information can be represented as a 4-D plenoptic function: ( , , , ) L x y u v . Although these two systems are similar in data recording, there exist some important differences between camera array system and plenoptic imaging system when transforming raw data into 4-D plenoptic function. Based on the imaging principle of these two different systems, this paper summarizes the distinction, which will be of great help for the researchers in this field. INTRODUCTION The human visual system uses binocular disparity to perceive the scene by fusing two images acquired by two eyes together. Conventional photos are two-dimensional, showing the location of captured scene but ignoring the depth information. To capture three-dimensional information of object scene, we must describe and record the light transmission. Adelson 1 put forward the concept of a seven-dimensional plenoptic function in 1991, which describes the light as a function of angle, wave length, time and location of the viewer, depicted as ( , , , , , , ) P x y z t θ φ λ . A typical model was proposed by Levoy and Hanrahan 2 in 1996, using two parallel planes to describe the location and direction information of light. Levoy and Hanrahan ignored the influence of wave length and time in Adelson’s model, and assumed that the intensity of light is constant during propagation. Therefore, the 7-D plenoptic function is simplified into a 4-D form, showed as ( , , , ) L u v x y , where ( , ) u v represents the direction of light and ( , ) x y represents the location. According to recording methods, there are two similar light field information captured systems, so-called camera array system and plenoptic imaging system. Camera array system is huge and complex, aiming to capture large amounts of light field data. The cave system designed by Q. Dai and K. Lee 3 at Tsinghua University, the 128 camera system designed by Stanford University 4,5 are both camera array systems. The plenoptic First author, Wei-jia Cai, School of biological science & medical engineering, Southeast University, Lane 2, Sipailou Road, Xuanwu District, Nanjing, China Other authors in the sequence, School of biological science & medical engineering, Southeast University, Nanjing, China