CAD*I Interface:

The CAD*I interface was developed in the framework of the ESPRIT Project 322 of the European Commission. The project was started in the year 1985 and had duration of five years. The results are recorded in the literature of Schlechtendahl (1988 and 1989). The emphasis of this project was placed on the data exchange among many CAD systems, the exchange of FEM and CAD models & the conception of a neutral databank for CAD data.

For the realization of data exchange reference architecture models for surface, 3-D wire frame, CSG and b-rep representations were established, and an interface for FEM applications was particular. For the description of CAD data structures, the specification language HDSL (High-level Data Specification Language) was designed. This language permits the expression of all of necessary elements of a CAD data structure along with the help of special language constructs.

Within the framework of this interface, an attempt was to be made to improve the deficiencies of IGES, SET and VDAFS which have the following problems.

• Many of the specifications are imprecise.
• The file formats are not suited for an efficient processor implementation.
• The structuring capabilities of the file format for CAD data are not adequate.
• The scope of the interfaces is very restricted.