Real-Time Dynamic Wrinkles Caroline Larboulette Marie-Paule Cani GRAVIR Lab, Grenoble, France

Motivations Animated wrinkles Important for realism –Cloth –Skin Currently painful under MAYA –Key shapes –Deformers Aims Real-time for computer games Applicable to a coarse animated mesh Easy to set up Static wrinkle Dynamic wrinkles

Previous Work Bump mapping [Blinn78, Boissieux00, Pasquariello01] –Efficient but undeformed silhouette Physically-based approaches [Wu94-99, Boissieux00] –Very realistic but slow Predefined Wrinkles [Viaud92] –Specific mesh incorporating wrinkles Displacement mapping [Volino99, Hadap99, Bando02] –The user designs the wrinkle pattern

Our Wrinkling Tool Basic Idea skin/cloth wrinkle because they tend to maintain area –Physically-based simulation, geometric constraints [sauvage04] ? Aims –Fast approximation of constant surface –No manual design of the wrinkles shapes –Provide control of location and main direction of wrinkles Our solution –A constant length wrinkling curve –Controls the mesh deformation in a region of influence

Wrinkling Curve 2D discrete curve of constant length Different propagation schemes Control of frequency, width of the bumps

Set up of the Wrinkling Tool 1.Draw a line segment End points are anchored to the mesh 2.Specify a region of influence Points under the green rectangle 3.Choose an attenuation profile

Mesh Deformation Mesh animated by standard skinning Wrinkles updated just before rendering Algorithm 1.Update 2D curve due to length changes 2.Refine mesh if needed 3.Compute mesh vertices displacements Height given by the coordinate along the curve Weighted according to the attenuation profile

Levels of Details Combination of bumps at different scales Absorbs compression at different resolutions

Multi-Wrinkles Combination of several wrinkles

Results: forehead wrinkles

Results: joint wrinkles Without our tool With our tool

Results: wrinkles on clothes Back Front

Video and demo

Conclusion Procedural technique –Mesh refined on the fly –Could depend on other parameters (camera) Easy-to-use for animators –Use of any existing skinning animation –Intuitive parameters and visual feedback Geometric constraints (length preservation) –Increases realism Real-Time

Future Work Curved Wrinkles Collision detection Combination with a dynamic flesh model

Thanks... Questions ?