Self-calibrating 360-degree shape measurement systems

For measuring the 3-D shape of complex objects by optical methods the optical sensor or the object have to be moved into multiple, overlapping measuring positions so as to view the entire surface. The resulting point clouds taken from the different views then have to be merged into a common coordinate system to obtain the final complete 3-D-view. Here we propose concepts of 3-D-measurement arrangements using structured-light illumination with a digital-light projection unit (DMD) to obtain a full-body view within a self-calibrating measurement strategy, whereas the necessary merging of the single views takes place fully automatically and is done without any marker on the object surface, objects features, other merging procedure or high accurate object/sensor handling system. On the basis of this strategy different mobile and stationary arrangements are proposed and realized. A first integration in an industrial process will be presented showing the power of this concept by measuring the complete 3-D shape of automotive parts and design objects within volume of 1 dm3 up to 1 m3. The measurements with this systems showed a coordinate measurement accuracy of up to 10-5 of the field size.