Geometric data transfer between CAD systems: solid models

The CAD/CAM community is showing great interest in the development of data exchange standards. This article highlights some aspects of the work accomplished during the first phase of the ESPRIT project CAD*1. Part of this work has resulted in a specification for the exchange of solid models, as well as in some pilot implementations of processors based on this specification. This work also contributes to the efforts of the International Standards Organization (ISO) in developing the Standard for the Exchange of Product Model Data (STEP). The authors present a summary of the CAD*1 approach, addressing the structure of neutral files for solids, entities, and attributes supporting three kinds of representations, facilities for the transfer of parametric designs, referencing library components, and other general mechanisms. Also is described the current state of the specification and processor implementations. An example of a CAD*1 neutral file is included. Results from cycle and intersystem solid model transfer tests are presented, showing the practicality of the CAD*1 proposal. B-rep model transfer results are discussed in some detail. Finally, the authors outline the relationship of this work with standardizatio

Automated geometry measurement of wheel rims based on optical 3D metrology

One of the economically most important branches is the automotive industry with their component suppliers. The high degree of automation in manufacturing processes, requires automated control and quality assurance equally. In this scope, we present a complex 3D measuring device, consisting of multiple optical 3D sensors, which is designed to capture the geometry of wheel rims. The principal challenge for automated measurements is the variety of rims with respect to design, dimensions and the production flow. Together with connected conveyers, the system automatically sorts good rims without interrupting the manufacturing process. In this work we consider three major steps. At first we discuss the application of the used 3D sensors and the underlying measuring principles for the 3D geometry acquisition. Therefore, we examine the hardware architecture, which is needed to fulfill the requirements concerning to the variety of shapes and to the measuring conditions in industrial environments. In the second part we focus on the automated calibration procedure to integrate and combine the data from the set of sensors. Finally, we introduce the algorithms for the 3D geometry extraction and the mathematical methods which are used for the data preprocessing and interpretation

A concept for applying VR and AR technologies to support efficient 3D non-contact model digitalization

In this paper a new interactive digitization concept for large real world objects is described using the virtual reality (VR) environment Elbe Dom. The method combines augmented reality (AR) technologies with a high quality display of textured three dimensional (3D) models. One focus is thereby the display of valuable information of the actual measuring process. The proposed method is a non-contact technique, especially applicable to objects with freeform and a size up to 5 m × 5 m × 3 m. The method achieves an accuracy value of less than 1 mm within the whole measuring volume