We present a novel methodology to precisely calibrate the subaperture views of an array of plenoptic 2.0 cameras. Such cameras consist of a micro lens array, and the image captured through them is a lenslet image that can be converted to a dense set of pinhole views, the so-called subaperture images. This camera array provides several dense multiview images at some sparse points of 3D space. To find the relative position of those views, simply using structure-from-motion creates misalignments due to the small disparities within each set. Additionally, a traditional calibration using calibration patterns will also fail due to the complicated objectives of plenoptic 2.0 cameras and artifacts when they are converted to subaperture views. In this paper, we propose two calibration steps (a) to register the sparse central subaperture views using Structure-from-Motion which makes it robust to artifacts in the subaperture views, and (b) to register all dense multiview sets per plenoptic camera using camera's lenses specifications, disparity and distance to the scene. These two steps are followed by a novel merging process of the former registrations, to achieve precise calibration parameters for all the subaperture views of the multi-plenoptic array. Experimental results objectively and subjectively demonstrate high accuracy of the calibration. We show a 10% smaller reprojection error than using a naive structure-from-motion approach and verify that our method is suitable for high precision view synthesis applications such as virtual reality and holography.

A tensor display is a type of 3D light field display, composed of multiple transparent screens and a back-light that can render a scene with correct depth, allowing to view a 3D scene without wearing glasses. The analysis of state-of-the-art tensor displays assumes that the content is Lambertian. In order to extend its capabilities, we analyze the limitations of displaying non-Lambertian scenes and propose a new method to factorize the non-Lambertian scenes using disparity analysis. Moreover, we demonstrate a new prototype of a tensor display with three layers of full HD content at 60 fps. Compared with state-ofthe-art, the evaluation results verify that the proposed non-Lambertian rendering method can display a higher quality for non-Lambertian scenes on both simulation and a prototyped tensor display.

Tensor displays are screens able to render a light field with correct depth perception without wearing glasses. Such devices have already been shown to be able to accurately render a scene composed of Lambertian objects. This paper presents the model and prototyping of a tensor display with three layers, using repurposed computer monitors, and extends the light field factorization method to non-Lambertian objects. Furthermore, we examine the relation and limitations between the depth-of-field and the depth range with Lambertian and non-Lambertian scenes. Non-Lambertian scenes contain out-of-range disparities that can not be properly rendered with the usual optimization method. We propose to artificially compress the disparity range of the scene by using two light fields focused on different depths, effectively solving the problem and allowing to render the scene clearly on both simulated and prototyped tensor display.

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.