Homography based identification for automatic and robust calibration of projection integral imaging displays

Abstract

Recent advances in the creation of microlens arrays as holographic optical elements allow the creation of projector-based see-through light field displays suitable for augmented reality. These systems require an accurate calibration of the projector with relation to the microlens array, as any small misalignment causes the 3D reconstruction to fail. The methods reported so far require precise placement of the calibration camera w.r.t. the lens array screen, which affects the display configuration. We propose a calibration approach which is more robust, and which allows free camera placement. Hence, it does not limit the capabilities of the system. Both a homography-based technique and structured light play a central role in realizing such a method. The method was tested on a projection-based integral imaging display system consisting of a consumer-grade projector and a digitally designed holographic optical element based micromirror array screen. The calibration method compensates for the lens distortion, intrinsics, and positioning of the projector with relation to the screen. The method uses a single camera and does not require the use of obtrusive markers as reference. We give an in-depth explanation of the different steps of the algorithm, and verify the calibration using both a simulated and a real-world setup.