Stefan Lanser A methodology for proving the accuracy of a system for high precision measurement of cutting tools is described. The tools are backlit by infrared illumination. Images are acquired by telecentric lenses and standard cameras and framegrabbers. The outer boundary of the tools is extracted by subpixel edge detection and is then approximated by lines and circular arcs.
All processing is done on standard hardware in real time.
To guarantee high precision measurements, all components of the system have to be evaluated. The key components are image acquisition, including illumination, lenses, filter, camera and framegrabber, and all operators used by the system, e.g., filtering, subpixel edge detection, and an appropriate polygon approximation. Since radial distortions of the images are quite large, even though telecentric lenses are used, camera calibration is essential for the accuracy of the system, since it allows the elimination of these distortions. The influence of each of the above components is discussed, and the behaviour of the complete system is analyzed.