Jingjing Shen: Trimmed NURBS to Untrimmed Subdivision

July 16 at 10:30am

in room Byron beige

Abstract: A NURBS model is usually created by several NURBS patches (trimmed or untrimmed) stitched together. The unavoidable gaps between trimmed patches have long been an issue in industry.  Because many applications, such as manufacturing and physical analysis, do not tolerate gaps, explicit boundary management is further required. We address this problem by converting trimmed NURBS models to untrimmed subdivision models. We focus on quadrilateral based subdivision schemes: Catmull-Clark subdivision (uniform) and NURBS-compatible subdivision schemes (non-uniform). For each trimmed patch, a subdivision mesh is automatically computed in two steps: a quadrilateral topology is constructed via a vector field based decomposition in domain space and the control points of a corresponding subdivision surface are then calculated in model space. The subdivision patches are merged to create a single subdivision surface. To simplify merging, shared boundary curves and the derivatives across them are used as constraints during the conversion. The converted model is gap-free and maintains the desired inter-patch continuity (up to $C^2$).

I am a PhD student in the Rainbow Group and my supervisor is Prof. Neil Dodgson. I work with Dr Jiří Kosinka and Malcolm Sabin. My PhD research is mainly about computer graphics and geometric modeling. My current project is about converting trimmed NURBS surfaces to subdivision surfaces. I’m also interested in quad remeshing, image processing, crowd and traffic animation. See http://www.cl.cam.ac.uk/~js2036/

I am currently visiting Inria (TITANE and GALAAD teams) in order to investigate isotropic meshing of NURBS surfaces through Delaunay filtering and refinement.

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