* modification on hollow bodies into solid bodies.<ref name=":3" />
Some CAD systems hashave a functionalityfunctionalities to compare geometry of two models.<ref>{{cite web|title=Compare Parts and Drawings|url=http://www.solidworks.com/sw/products/3d-cad/compare-parts-drawings.htm}}</ref><ref>{{cite web|last1=Madhavi|first1=Ramesh|title=Comparing Drawings, Models and PCBs with PTC Creo View|url=http://www.ptc.com/cad-software-blog/comparing-drawings-models-and-pcbs-with-ptc-creo-view}}</ref> So, user can compare the model before and after translation from one CAD to another one to estimate quality of the translation, and to fix found defects. But often such functionalities can compare only [[tessellation]]s of two models. It is really hard algorithmic problem to compare topological elements of two 3D models and restore their associativity to show groups of modified faces, because there are very different representation of geometry data in different CAD systems, but sometimes it is possible. For instance, the component LEDAS Geometry Comparison based on [[C3D]] kernel can be integrated in [[CAD]] system (like [[Autodesk Inventor]], <ref>{{cite web|title=LEDAS Geometry Comparison Licensed for Inventor Plug-in|url=http://www.tenlinks.com/news/ledas-geometry-comparison-licensed-for-inventor-plug-in/|date=Apr 21, 2016}}</ref>) to compare 3D models and pinpoint all of the differences between them.<ref>{{cite web|title=Geometry Comparison from LEDAS now supports all major MCAD formats with DATAKIT libraries|url=http://www.datakit.com/en/news/geometry-comparison-from-ledas-now-supports-all-major-mcad-formats-with-datakit-libraries-137.html|date=February 17, 2015}}</ref>
