3D-camera

Industrial- and multimedia applications need cost effective, compact and. flexible 3D profiling instruments. In the talk we will show the principle of, applications for and results from a new miniaturized 3-D profiling system for macroscopic scenes. The system uses a compact housing and is usable like a camera with minimum stabilization like a tripod. The system is based on common fringe projection technique. Camera,and projector are assembled with parallel optical axes having coplanar projection and imaging planes. Their axes distance is comparable to the human eyes distance altogether giving a complete system of 21x20x11 cm size and allowing to measure high gradient objects like the interior of tubes. The fringe projector uses a LCD which enables fast and flexible pattern projection. Camera and projector have a short focal length and a high system aperture as well as a large depth of focus. Thus, objects can be measured from a shorter distance compared to common systems (e.g. 1 m sized objects in 80 cm distance). Actually, objects with diameters up to 4 m can be profiled because the set-up allows working with completely opened aperture combined with bright lamps giving a big amount of available light and a high Signal to Noise Ratio. Normally a small basis has the disadvantage of reduced sensitivity. We investigated in methods to compensate the reduced sensitivity via setup and enhanced evaluation methods. For measurement we use synthetic wavelengths. The developed algorithms are completely adaptable concerning the users needs of speed and accuracy. The 3D camera is built from low cost components, robust, nearly handheld and delivers insights also into difficult technical objects like tubes and inside volumes. Besides the realized high resolution phase measurement the system calibration is an important task for usability. While calibrating with common photogrammetric models (which are typically used for actual fringe projection systems) problems were found that originate from the short focal length and the extreme opening angle of the system as well as the large depth of focus. The actual calibration method is outlined and current problems are shown. An improved calibration of the system is discussed for improved results in future.