Pattern-free Plenoptic 2.0 Camera Calibration

The plenoptic 2.0 camera is a light field acquisition system consisting of a main lens and a micro-lens array (MLA) at a non-focal distance of the main lens. While it allows to retrieve the geometry of the scene, the distances between the main lens, the MLA and the sensor are usually unknown. Therefore, the use cases for plenoptic cameras stay limited while they have more potential applications such as virtual reality, provided that their camera parameters are precisely known. In this paper, we present a pattern-free calibration method to retrieve the plenoptic camera's intrinsic parameters from the rendered subaperture images, i.e. the distance from main lens to the MLA and sensor, the focal length and the principal point. The proposed method utilises the relation between scene's distances, i.e. depth, and the subaperture images' micro-disparities, which contains information about the camera parameters. To the best of our knowledge, it is the first pattern-free calibration method for plenoptic 2.0 cameras. We compare the parameters obtained using our method applied to subaperture images rendered from three different software tools (Plenoptic Toolbox, Reference Lenslet content Convertor, and Lenslet to Multiview) with an open-source pattern-based method (Compote). The proposed pattern-free calibration method has consistent camera parameters with the traditional pattern-based calibration method. We therefore reliably obtain the intrinsic parameters of any plenoptic camera from its captured images, even in the absence of any calibration pattern.