Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A C.6.4. Conversion of 3D models from one format to another. Product data quality is especially important when models are being translated from one format to another. Defects in geometry or topology of models may cause translation programs to fail. In some cases 3D models may not sew into valid solids in the receiving system. Faces or entire sections of models may be missing. Fixing such errors after translation is time-consuming and expensive. It is more cost-effective to check models for defects before they are translated to other formats.
The diagrams below illustrate several different processes that data conversion can take: Figure 7. Model translation processes. When the model source is a CAD system, the sender should correct errors in the CAD system. When the source is a standard format or long-term storage archive, data defects should be healed prior to translation. In all of the above cases, it is assumed that geometry and topology but not parametric features are translated between two systems. When a process requires that parametric features, assembly mates, and associative drawings also be translated, then the conversion process is commonly referred to as re-mastering, which is discussed in the next section. C.6.5.
Re-mastering of 3D model data. Re-mastering is the process of recreating an intelligent model with parametric features in a CAD systems that is different from the one in which it originated. There are currently no fully automated conversion tools for re-mastering all classes of parametric feature-based 3D models. Simple parametric features such as blocks, grooves, and round holes can be translated automatically with high fidelity. But more sophisticated features, such as lofts, sweeps, blends, drafted faces, and fillets may be distorted or fail in translation. People can quickly recognize when such errors occur and make decisions about how to correct them.
That’s why feature-translation software relies on human intervention, which also is subject to human error. 80