GEOMETRIC DESIGN OF A MULTISENSOR STRUCTURED LIGHT RANGE DIGITIZER

An optical noncontact 3-D range digitizer based on projection of 2-D structured light patterns and multiplexed charge injection device (CID) camera sensors has been developed. The system acquires digitized data in 0.75 s and allows 360-deg examination of the subject's head and facial surface features in less than 1 s, making it suitable for digitizing children as well as adults. The resultant 3-D surface data is suitable for computer graphics display and manipulation, numerically controlled replication, and further processing such as surface measurement extraction. The digitizer uses a set of six stationary sensors positioned about the subject. A sensor consists of a pattern projector and a solid state video camera. This device allows quantitative volume measurements and employs no harmful ionizing radiation. The cost of a scan with this technology is substantially less than that of alternative means of collecting 3-D surface data sets, such as by stereometric, moire fringe, and single-point digitization. This system was geometrically designed such that any surface of the head or facial area was independently digitized by a minimum of two sensors and to capture areas normally occluded with other techniques. The dimensions of the structure were derived to satisfy physical constraints placed on its overall size. The camera and projector orientations in space, the distance from the lens centers to the center of the digitizing volume, and the lens focal lengths were determined analytically. To reduce cost, a standard lens nearest the analytical value was used. Based on the standard size lens, the field of view was calculated.