# How to know if a model contains B-Rep or Tessellated bodies **URL:** \ **Category:** HOOPS Exchange\ **Tags:** how-to, tessellation\ **Created:** [January 17, 2022, 5:00am UTC](https://forum.techsoft3d.com/t/how-to-know-if-a-model-contains-b-rep-or-tessellated-bodies/1502 "2022-01-17T05:00:00Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![gabriel.peragine](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.techsoft3d.com/gabriel.peragine/32/1535_2.png) [@gabriel.peragine](https://forum.techsoft3d.com/u/gabriel.peragine)\ **Post date:** [January 17, 2022, 5:00am UTC](https://forum.techsoft3d.com/t/how-to-know-if-a-model-contains-b-rep-or-tessellated-bodies/1502/1 "2022-01-17T05:00:00Z")
CAD files embed two kind of data for the 3D bodies: BRep and Tessellation. A **BRep** body is described by mathematical parameters and a topology. In order to display a BRep body, HOOPS Exchange evaluate the parameters and generate a tessellation. The BRep parameters are accessible in the PRC. A **Tessellated body** , is simply a list of vertices organized in faces. Depending on the format, the PRC you get from a HOOPS Exchange conversion may contains BRep, Tessellation or both. The tessellation may be generated by HOOPS Exchange or extracted from the CAD data. [More info](https://forum.techsoft3d.com/t/faq-how-does-exchange-handle-tessellation-data-while-reading-a-cad-file/1498) ## Instructions After the convertion of a model to PRC, you can identify which entities are B-Rep and which are tessellated bodies. - Traverse the tree to the Representation Item level - Check the Representation Item type - **A3DRiPolyBrep:** this is a tessellated body. In HOOPS Demo Viewer it is described as “Faceted solid” - **A3DRiBrepModel:** this is a B-Rep body, you can parse its parameters and explore its topology. - **A3DRiSet:** this a collection of A3DRiRepresentationItem. You need to check the type of the children of this entity.