Sugihara, Masamichi2009-08-202009-08-2020092009-08-20http://hdl.handle.net/1828/1554Implicit surfaces offer many advantages for sketch-based modeling systems, such as blending, CSG, and a procedural object hierarchy. Free-form deformation (FFD) is also extremely useful in this context, however existing FFD approaches do not support implicit surface representations, and FFD lattice manipulation is time-consuming compared to sketch-based techniques. In this thesis, an FFD technique suitable for implicit surface representations is described. To enhance real-time feedback, the problem is split into an approximate formulation used during interactive deformation, and a more robust variational technique which preserves desirable scalar field properties. As an interface to manipulate the deformation, a sketch-based volumetric peeling interface is introduced. The user's task is to draw a curve on the surface, and pull or push the surface to the desirable position via the curve. Subsequently, the deformation is automatically defined. This technique has been implemented in a prototype implicit FFD system called Taco. Results created in Taco show that a desirable deformation can be easily achieved while preserving implicit properties.enAvailable to the World Wide WebComputer GraphicsImplicit SurfacesUser InterfacesUVic Subject Index::Sciences and Engineering::Applied Sciences::Computer scienceThesisSugihara, M., de Groot, E., Wyvill, B., and Schmidt, R. A sketch-based method to control deformation in a skeletal implicit surface modeler. In Proceedings of the 5th Eurographics Workshop on Sketch-Based Interfaces and Modeling (2008), pp. 65-72.