Automated Calibration Technique for Photogrammetric System Based on a Multi-media Projector and a Ccd Camera

Recently multi-media projectors became commercially available for using in 3D reconstruction application. They have a number of features which make them attractive for using in photogrammetric application. The main of these features are high technical characteristics (such as brightness, contrast, signal/noise ratio, resolution) and a reasonable price. And the main advantages of multimedia projector is a capability of intellectual lighting for applying smart algorithms for accurate correspondence problem solution. The traditional configuration of a close range photogrammetric system is two calibrated cameras and a structured light projector. In such a scheme the projector has no need to be calibrated. Projector calibrating allows to increase productivity of 3D reconstruction system and to reduce its cost due to one CCD camera eliminating. To apply common bundle adjustment procedure for a projector calibration it is necessary to solve a problem of determining spatial coordinates for reference points lighted (or “observed”) by the projector. Two techniques for projector calibration are presented. Both of them use standard bundle adjustment program and planar test field with coded targets for calibration procedure automation. The first technique uses two calibrated cameras for producing “virtual” spatial test field. The second technique supposes generating synthetic “images” of a test field observed by the projector. Then the parameters of interior orientation for the camera and the projector are found by standard bundle adjustment procedure. * 7, Victorenko str. Moscow, Russia 125319. Phone: +7-499-157-3127, Fax: +7-499-157-3900, e-mail: [email protected]