## Section: Contracts and Grants with Industry

### Lumiscaphe

Participants : Pierre Alliez, Mariette Yvinec.

In collaboration with Jean-Christophe Leducq (Lumiscaphe) and Alain Tayeb (master intern in our project-team).

Our goal was to devise a new intersection oracle for the mesh generators of CGAL, specialized for parametric NURBS surfaces (common in CAD). The main added value to proceed by Delaunay refinement and access the input surface through an oracle is to be able to mesh the union of NURBS surface patches at once instead of meshing each patch separately. For models comprising hundreds of patches we obtain meshes with lower complexity and with only well-shaped triangles. For a given intersection query with a line segment, our methodology consists of using a Newton iteration in the parameter space of all NURBS patches in order to track the intersection point(s). As future work we wish to elaborate upon a robust version of the intersection oracle, so as to deal with defect-laden NURBS surfaces. The current prototype code will be later consolidated and added to the CGAL library.