Corner-Based Geometric Calibration of Multi-Focus Plenoptic Cameras

Sotiris Nousias, Francois Chadebecq, Jonas Pichat, Pearse Keane, Sebastien Ourselin, Christos Bergeles; Proceedings of the IEEE International Conference on Computer Vision (ICCV), 2017, pp. 957-965

We propose a method for geometric calibration of multi-focus plenoptic cameras using raw images. Multi-focus plenoptic cameras feature several types of micro-lenses spatially aligned in front of the camera sensor to generate micro-images at different magnifications. This multi-lens arrangement provides computational-photography benefits but complicates calibration. Our methodology achieves the detection of the type of micro-lenses, the retrieval of their spatial arrangement, and the estimation of intrinsic and extrinsic camera parameters therefore fully characterising this specialised camera class. Motivated from classic pinhole camera calibration, the presented algorithm operates based on a checker-board's corners, retrieved by a custom micro-image corner detector. This approach enables the introduction of a re-projection error that is used in a minimisation framework. Our algorithm compares favourably to the state-of-the-art, as demonstrated by controlled and free-hand experiments, making it a first step towards accurate 3D reconstruction and Structure-from-Motion.