Intuitive Editing of Surface Meshes

Written by Marc Alexa (external)

Marc Alexa

Technical University of Berlin, Germany

Keynote talk in English
WSCG 2007
January 30, 2007
University of West Bohemia


presentation slides (11MB PPT)


Surface editing operations commonly require geometric details of the surface to be preserved as much as possible. I argue that geometric  detail is an intrinsic property of a surface and that, consequently, surface editing is best performed by operating over an intrinsic surface representation. Different ways of representing the intrinsic geometry and the boundary constraints result in alternatives for the properties of the modeling system. In particular, the Laplacian and several extensions are reviewed.

Based on this representation, useful editing operations can be developed: Interactive free-form deformation in a region of interest  based on the transformation of a handle, transfer and mixing of geometric detail between two surfaces, and transplanting of a partial  surface mesh into another surface. In particular,  the handle can be a curve such as a silhouette or a sketch on the surface.  Subsequently, an edit can be carried out by sketching a new, view-dependent handle position or by indirectly influencing differential properties along the sketch.

The main computation involved in all operations is the solution of a sparse linear system, which can be done at interactive rates. We demonstrate the effectiveness of this approach in several examples, showing that the editing operations change the shape while respecting the structural geometric detail.


Marc Alexa is a Professor in the Faculty of Electrical Engineering and Computer Science at the Technical University of Berlin and heads the Computer Graphics group. He is primarily interested in representing shapes and their deformation, using point sampled geometry, implicit surfaces, explicit representations, and linear spaces of base shapes. For his earlier work on morphing he received a PhD in Computer Science from Darmstadt University of Technology. He has presented and lectured on topics related to shape representations at SIGGRAPH and other conferences. Marc Alexa has been a co-chair and has served as a member of several committees of major graphics conferences.

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