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 Geometric texture synthesis [Bhat et al 2004] [Lagae et al 2004]
Related Work Common parameterizations [Kraevoy and Sheffer 2004] [Schreiner et al 2004] [Allen et al 2003] Deformation transfer [Sumner and Popovic 2004]
Related Work Generative modelling [Snyder 1992] Wires [Singh and Fiume 1998] Poisson-based editing [Yu et al 2004]
Related Work Teddy [Igarashi et al 1999, 2001]
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
Curve Selection Planar intersection curves Silhouette curves Parallel or rotating slices 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 System iteratively copies offsets to target
Curve Analogies Joint neighbourhood matching Find best t with A(t) ~ B(tcurr), A’(t) ~ B’(tcurr) 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
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 Parallel local frames
Influence Radius Radius of influence of each curve can be varied Can also vary fall-off function
Influence Radius Radius of influence of each curve can be varied Can also vary fall-off function
Influence Radius Radius of influence of each curve can be varied Can also vary fall-off function
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
Results
Results
Results Harmonic fields [Ni et al 2004]
Future Directions Better Curve Analogies Avoid orientation flipping using surface information Use intrinsic curve parameterization to accelerate Spatial influences near intersections
Future Directions More curve families Iso-parameter curves Signal-specific curves Suggestive contours [DeCarlo et al 2003]
Future Directions Poisson-based surface transformation Can we use Image Analogies similarly?
Thanks Funded in part by a grant from the NSF (CCR-0086084) Software/source code at: http://graphics.cs.uiuc.edu/~zelinka