The aim of reverse engineering is to create a computer-aided design (CAD) model of an existing physical object. This paper deals with technology for acquiring measured point data by use of an optical 3-D measuring system. This system is suited for measuring objects, at a high speed and in a high density, which have smooth shapes and character areas with steep slopes. Smooth curves are approximated by fitting non-uniform cubic B-spline curves with curvature taken into consideration. Free-form surfaces in higher-order continuity are derived from the fitted B-spline curves as the boundary curves of patches. A strategy for remeasurement is proposed to extract character areas in order to generate a series of free-form surfaces, and techniques are also proposed to connect fitted B-spline curves with surfaces by use of pseudo vertices. The results of the experiments show that the proposed methods are effective for generating free-form surfaces.

This paper presents a new multi-probe method for accurately measuring straightness profiles of cylinders. This scanning probe method is developed from the traditional three-probe method, which can measure the profile accurately without the influence of motion errors of the scanning stage. Two sets of three-probe method sensor units are used in the developed method so that the zero-adjustment errors between the probes can be evaluated. The two sensor units are placed in the two sides of the cylindrical workpiece and are used to scan the two opposed generatrices of the cylindrical workpiece simultaneously. The workpiece is then rotated 180 degrees and scanned by the probe units again. The zero-adjustment error, as well as the straightness profiles of the workpiece can be accurately evaluated from the output data of the two measurements. The effectiveness of this method is confirmed by theoretical analyses and experimental results. The problem in another method, which was previously used by the authors to measure the zero-adjustment error between the probes, is also discussed.

This paper presents an Internet Based Roundness and Cylindricity Analysis System, which applies Java and Internet technology to engineering metrology. The package includes most of the standardized and advanced analysis tools for roundness and cylindricity. The most distinct feature of this package is that it can run on the Internet, which enables platform independent and remote analysis of roundness and cylindricity data.

Due to the cylindrical shape of drill-holes and inner threads the acquisition of high-resolution images has not yet been solved satisfactorily. Different possibilities for taking pictures from the inside of a drilled hole are reviewed and evaluated with respect to the quality of the images. Results show, that a ring-shaped CMOS-Sensor works best for the purpose of automatic inspection.
Additionally, the analysis of these images requires a special algorithmic approach, which is able to take care of the cylindrial shape of the object. To achieve this, the use of the Z-transformation is recommended for processing of such images, and it is shown to be superior to other image processing operators.

Many optical methods of geometrical quantities' measurements need continuous, precise, and high speed determination of positions of light beams interacting with the measured surface. Existing photodetectors, namely chargecoupled devices (CCDs) and position sensitive detectors (PSDs) in many cases do not comply with these demands. We are developing a new device with superior characteristics. It is based on the domain wall motion in a transparent ferromagnet, a so-called orthoferrite. The velocity limit of the domain wall motion in orthoferrite crystals is extremely high: 20 km/s. The device consists of an orthoferrite plate, an analyzer and a single point photodetector. It can measure positions of the light spots continuously with submicrometric accuracy. The sampling rate of the measurements can reach1 MHz. The application of the device to the angular measurements is briefly described.