New Techniques to Compensate for Mistracking within Stereoscopic Acquisition Systems

Abstract

When a lens is mounted to a camera, there is an inevitable mechanical tolerance associated with the lens optical center and another associated with the camera optical center. These separate tolerances can be additive or subtractive for a given lens-camera combination (both tolerances entail unpredictable additive and subtractive limits). This aberration poses the greatest challenge to the imaging alignment of stereoscopic rigs. Lens operational dynamics add another variable differential in terms of small mistracking between angle of view over the focal range of a zoom lens pair, mistracking between their optical focus, and mistracking between their aperture settings. Many workers in the field of three-dimensional (3D) technology are diligently seeking practical and cost-effective solutions to these disparities. This paper describes recent developments that entail automatic and dynamic corrections for these differential tolerances. New software in the digital servo systems that operate lens zoom, iris, and focus control allows entry of compensation data that corrects for mistracking errors in these three operational functions. Separately, a novel development by 3D rig designer Microfilms of France uses the technology of optical image stabilization built into a high-definition (HD) television lens to implement automatic realtime correction of both the fixed and the dynamic optical miscentering errors between two lenses. A different image stabilization technology—built into the lenses of integrated HD lens–camcorders (increasingly popular for small, handheld 3D rigs)—allows corrections for the fixed optical miscentering between any two such systems at specific focal length settings.