Optical 3D measurement techniques are state-of-the-art for highly precise, non-contact surface scanners - not only in industrial development, but also in near-production and even in-line configurations. The need for automated systems with very high accuracy and clear implementation of national precision standards is growing extremely due to expanding international quality guidelines, increasing production transparency and new concepts related to the demands of the fourth industrial revolution. The presentation gives an overview about the present technical concepts for optical 3D scanners and their benefit for customers and various different applications – not only in quality control, but also in design centers or in medical applications. The advantages of DMD-based systems will be discussed and compared to other approaches. Looking at today’s 3D scanner market, there is a confusing amount of solutions varying from lowprice solutions to high end systems. Many of them are linked to a very special target group or to special applications. The article will clarify the differences of the approaches and will discuss some key features which are necessary to render optical measurement systems suitable for industrial environments. The paper will be completed by examples for DMDbased systems, e. g. RGB true-color systems with very high accuracy like the StereoScan neo of AICON 3D Systems. Typical applications and the benefits for customers using such systems are described.
The possibility for testing and calibration of industrial robots becomes more and more important for manufacturers and users of such systems. Exacting applications in connection with the off-line programming techniques or the use of robots as measuring machines are impossible without a preceding robot calibration. At the LPA an efficient calibration technique has been developed. Instead of modeling the kinematic behavior of a robot, the new method describes the pose deviations within a user-defined section of the robot's working space. High- precision determination of 3D coordinates of defined path positions is necessary for calibration and can be done by digital photogrammetric systems. For the calibration of a robot at the LPA a digital photogrammetric system with three Rollei Reseau Scanning Cameras was used. This system allows an automatic measurement of a large number of robot poses with high accuracy.
Nowadays high-resolution cameras are used more frequently for solving measuring problems. Applications range from 2D- to complex photogrammetric 3D-measurements. Using a digital image recording system for measuring purposes however requires an exact knowledge about the reachable accuracy, taking into account the different modules like lenses, sensor, analog- to-digital converter and components, which in most cases are necessary to get a higher resolution (for example shifting devices or reseau plates). At the IPB a photogrammetric procedure was developed, which allows a fast determination of the geometrical efficiency and a calibration of any digital image recording device. A testfield with points, which 3D- coordinates must be known only approximately, is recorded in different images, which defines a geometrically stable photogrammetric network. All measured image points are used to compute a bundle adjustment. The results of the computation show the overall geometric accuracy of the system and the effect of different system parameters (for example lens distortion and pixel affinity). The paper gives a detailed description of the method and shows results of the evaluation and calibration of different high resolution camera systems.
For the description of deformations and dummy motions during the crash, the Volkswagen AG uses 16mm high-speed drum cameras with frequencies of 400 pictures/sec. A system for a digital photogrammetric evaluation of the 16mm images has been developed. Several images of one epoch are completely digi- tized by a VIDEK Megaplus CCD-camera. After the measurement of signaled points in the digital images and a first orientation of the pictures using a graphic display, object coordinates are to be computed by a bundle adjustment. The interior orientation of the different cameras are deter- mined by simultaneous calibration. First experiences with the handling of the system, which in principle is useful for the photogrammetric evaluation of any digital images, and the precision of the point determination will be presented.
High resolution digital cameras have become an interesting tool in digital photogrammetry. At the Technical Uniyersity of Braunschweig, Department of Photogrammetry and Image Processing, several cameras, including the Reseau Scanning Camera, Videk Megaplus and the ProgRes 3000, have been under investigation for photogrammetric purposes. The different ways to achieve high resolutions are briefly described, as well as the method of investigation, including digital point measurement and testfield triangulation. The results are presented in the last part together with practical experiences made in camera handling.