Surface-geometry measurement using an untracked range-sensor head

摘要

The demand to provide greater flexibility in surface-geometry measurement of free-form objects, has led to range sensors which are permitted continuous free motion. However, most devices employ mechanical linkages instrumented with position sensors, or optical or magnetic tracking sensors to determine the position and orientation of the moving range-sensor head. These additional sensors limit the working volume, impede the free movement of the range sensor, or restrict the material allowed in the work environemnt. This paper preents a method of surface-geometry measurement by a laser-camera range sensor head, which is permitted continuous motion in space, without the need to track its position and orientation by additional sensors. The method balances the need to capture sufficient range information in each image, to provide adequate overlap for registration of successive views, and the goal of rapid acquisition of surface geometry with minimal redundant data. Several profiles are captured in a single camera image to comprise a range view, and range views are acquired with little movement between viewpoints. Global registration of views of a sequence is carried out by computing adjacent-views registration transformations using a transformation-parameter optimization to minimize closest-point distances between views. Simulations of the range-sensing method, performed on adjacent-view pairs and a 49-view sequence, yielded mean absolute global registration errors of 0.032 mm and 0.472 mm, respectively. This is acceptable for many surface modeling applications. The method is applicable when the range-sensor head and object have continuous unknown motion.