3D Reconstruction through the Ray Calibration of an Optically Distorted Stereophotogrammetric System

The process of camera calibration is an important step in image based 3D reconstruction to determine triangulating rays for each corresponding point between two views. Standard techniques for determining the parameters and the supplemental polynomial distortion corrections of perspective cameras are unable to sufficiently describe images with strong distortion effects as seen in those taken with wide angle lenses. By considering a generalized imaging model in this study, the technique of Ray-Based Calibration is used to directly determine triangulating rays for each camera pixel by imaging a temporally encoded TFT displaying a sequence of band limited patterns in two different positions. It is demonstrated that the Ray-Based Calibration method is still able to reconstruct a temporally encoded object accurately when stereoscopically imaged by cameras that are strongly distorted by a wide angle lens, while the standard calibration techniques fail.