TOOLS FOR THE INTEROPERABILITY AMONG CAD SYSTEMS

The lack of interoperability among CAD systems due to the hard task to exchange efficiently CAD data is addressed in this work. The tools useful to guarantee the data exchange are analyzed and the strategies to be followed to prepare a CAD model and minimize information loss are investigated. The most critical problems in data exchange are the different internal mathematical representation schemes and the internal accuracy of the geometric definitions in the modeling kernel of the various CAD systems. In particular, the problems arise from the accuracy and the convergence criteria used when performing calculations with curves and surfaces. All this can occur either within the original system or during the pre- and post-processing phases of CAD data, performed with neutral format, like IGES or STEP. Inaccuracy can be due to several factors, like the different implementation of algorithms used during the translation, or when geometries are to be converted in another representation forms, or due to geometrical and topological model inconsistency. But the problems can also arise from inadequate geometric modeling in the original CAD environment. Some CAD systems do offer very useful tools to check and repair original and imported model geometry but, unfortunately, they do not automatically avoid information loss, especially when the models are complex. The author analyses what healing tools are available and important to repair a CAD model, and how to use them, as well as how to prepare a model to ensure CAD interoperability and prevent failure in data exchange via neutral standard formats.