The U.S. Army, and BRL-CAD in particular, should be represented at meetings where IGES specifications and product data exchange standards are discussed and developed. Such representation has the potential to eliminate some of the difficulties of IGES translation for BRL-CAD and may avoid future problems arising from decisions similar to those made in the past by the IGES committee (the separation of CSG and BREP, and the limited cases of certain CSG primitive solids). Private industry is heavily represented at these meetings, and without some demonstration of interest and influence by BRL-CAD users/developers, all decisions made by the committee will be in the best interests of the attendees, regardless of the consequences they may hold for BRL-CAD.
As IGES is developing to maturity, another candidate for product data exchange is still in its infancy. Product Data Exchange Using STEP (PDES) is a more comprehensive approach under development by an international organization (which includes the IGES committee as one part). The STEP portion of the PDES acronym represents the Standard for the Exchange of Product Model Data, which is the actual candidate for an international standard, while PDES is the U.S. effort supporting STEP. A satisfactory discussion of PDES is beyond the scope of this report, but the reader should be aware that PDES's potential use is considerably more than a mere replacement of IGES. PDES encompasses an order of magnitude greater scope and application than IGES. Whereas IGES is concerned with the product definition of an object (part, component, system), PDES's objective is to address the complete range of an object's product data (i.e., data relevant to the product's complete life cycle). As an analogy, comparing IGES to PDES is like comparing nroff to the UNIX operating system in terms of total scope and functionality.
Work on PDES dates back to the mid-1980s, but PDES has not demonstrated a capability that compares to IGES's capability when IGES was a little more than a half-decade old. That statement is not a criticism of PDES, but merely accentuates the enormous task that is the PDES effort. It is predicted that possibly in ten years, PDES will be the method of choice for exchanging product definition data, including solid models. If PDES is eventually accepted as a standard by the International Standards Organization (ISO), then it is definitely in the best interests of the ARL to be actively participating in the development of this new specification. Many of the same people who developed IGES are heavily involved in PDES, and the ARL should be involved to insure that the development of specifications do not exclude capabilities demonstrated by BRL-CAD.
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