Mesh Modelling With Curve Analogies Steve Zelinka Michael Garland University of Illinois at Urbana-Champaign

In a Nutshell

Overview Motivation Related Work Details of our Approach Results Curve Selection Surface Transformation Results Future Work

Motivation Reduce artistic skill required for modelling Solution: Modelling by Analogy A : A’ :: B : ? Images [Hertzmann et al 2001] Curves [Hertzmann et al 2002]

Mesh Analogies? User burden Unsolved technical issues : :: : ?

Related Work Wires [Singh and Fiume 1998] Excellent control over editing Highly skilled artist required

Related Work Teddy [Igarashi et al 1999] Intuitive sketch-based interface Limited class of models

Approach Overview Select surface curves Transform surface curves with Curve Analogies Transform the surface 2D sketch-based manipulation Simple implementation

Curve Selection Planar intersection curves Parallel or rotating slices Orthogonal to skeleton

Curve Selection Planar intersection curves Silhouette curves Parallel or rotating slices Orthogonal to skeleton Silhouette curves

Generality Issues Features controlled only on and along curves Use orthogonal, intersecting sets of curves Multiple passes

Curve Analogies User sketches unfiltered, filtered curves Identical parameterizations required Based on joint neighbourhood matching Neighbourhoods must be aligned before comparison

Surface Transformation Similar to Wires Vertices near a curve track movement of their closest points on the curve

Surface Transformation Similar to Wires Vertices near a curve track movement of their closest points on the curve Vertex movement inversely proportional to distance to curve

Influence Radius Radius of influence of each curve can be varied

Influence Radius Radius of influence of each curve can be varied

Influence Radius Radius of influence of each curve can be varied

Multiple Curves Vertices can be influenced by multiple curves Candidate position from each influencing curve Final position weighted average of candidates

Results Curve Analogies Dominate compute time Can be difficult to control

Future Directions Better Curve Analogies Avoid orientation flipping using surface information Use intrinsic curve parameterization to accelerate

Future Directions More curve families Iso-parameter curves Signal-specific curves Suggestive contours [DeCarlo et al 2003]

Future Directions Influence radius Use spatially-based multi-analogies Adaptive setting Dynamics-based Surface Transformation Prevent self-intersections Allow topology changes

Thanks Funded in part by a grant from the NSF (CCR-0086084) Contact: Steve Zelinka zelinka@uiuc.edu Michael Garland garland@uiuc.edu