A Sketching Interface for Garment Design

National audienceThe range of approaches used for clothing virtual characters is large: for incidental characters, the clothing may be no more than a texture map. For lead characters in feature films, full-fledged physical simulation of detailed cloth models may be used. And in the midrange, simple skinning techniques, combined with texture mapping, are common, providing some deformation of clothing as the character moves, but no physical realism. There are three problems one can associate with clothing virtual characters: the design of the clothes (tailoring), placing them on the character (dressing), and making them look physically correct (typically through simulation). The process of tailoring involves choosing the cloth and fitting it to the body, often making adjustments in the patterns of the cloth to adapt it to the particular person's body shape, and then sewing it. For virtual characters, clothing often has no "patterns" from which it is sewn, instead it is represented by a simple polygonal mesh that is constructed to fit the body. It's currently tedious to construct such meshes even without the issues of patterns and stitching. It's sometimes done by directly incorporating the cloth mesh into a character's geometric model, so that the character doesn't actually have legs, for instance, but just pants (see figure 1.1). In this case physical simulation is no longer a possibility, and when a character needs new clothes, it must be largely re-modeled. An alternative approach involves drawing pattern pieces for a garment and positioning them over the naked form of the character, defining stitching constraints, etc. This can be tedious, especially when the character is not important enough to merit this amount of effort; it also requires an understanding of how cloth fits over shapes, although the actual pattern-and-stitching information may not be relevant after the tailoring is completed (except in the rare case where the physical properties of the cloth -- was it cut on the bias? Does the cloth resist folding along one axis? -- are later used in a full-fledged physical simulation). Our approach combines tailoring and dressing into a single step to create a mesh that's suitable for later simulation or skinning approaches. The idea is to make it easy to generate simple garments that are adapted to an existing model. We believe that most people know better how to draw garments than the patterns which are needed to sew them. The aim of this work is thus to explore the use of a sketch-based interface for quickly constructing 3D virtual garments over a character model. This report describes simple solutions to the problems of shape generation and placement of the clothing. The resulting system is so easy to use that it takes only few minutes to create a simple garment