Relief: A Modeling By Drawing Tool

Relief: A Modeling by Drawing Tool David Bourguignon 1 Raphaëlle Chaine 2 Marie-Paule Cani 3 George Drettakis 4 1 Princeton University / INRIA Rocquencourt 2 LIRIS / CNRS / UCBL 3 GRAVIR / INP Grenoble 4 REVES / INRIA Sophia-Antipolis

Outline Motivation Previous Work Tool Workflow Reconstruction Adaptive Sampling & Depth Inference Tool Interface Results

On Users Most people draw Writing alternative Few people sculpt Play-Doh days long gone Materials difficult to handle

Goals Use 2D tools to perform 3D operations

Goals Use 2D tools to perform 3D operations Model global and local surface

Goals Use 2D tools to perform 3D operations Model global and local surface Input: just plain strokes

Goals Use 2D tools to perform 3D operations Model global and local surface Input: just plain strokes Output: triangle mesh

Outline Motivations Previous Work Tool Workflow Reconstruction Adaptive Sampling & Depth Inference Tool Interface Results

Previous Work Depth painting [Williams, 1990] +

Previous Work Gradient editing [van Overveld, 1996]

Previous Work Maya 6.0 Artisan [Alias, 2004]

Tool Workflow First step: drawing input Displacement map mid-grey = 0 white > 0 black < 0 Model of 3D sphere Pencil Brush

Tool Workflow First step: drawing Displacement map 2D shape boundary (in green) defines drawing mask

Tool Workflow First step: drawing Displacement map 2D shape boundary Displacement regions (from 2 maps)

Tool Workflow Second step: modeling Displace existing vertices

Tool Workflow Second step: modeling Displace existing vertices Create new surface patch

Tool Workflow Changing viewpoint Modeling by drawing Changing viewpoint

Reconstruction Based on evolving pseudo-manifold [Chaine, 2003]

Reconstruction Based on evolving pseudo-manifold [Chaine, 2003] Satisfy our requirements Arbitrary number of connected components

Reconstruction Based on evolving pseudo-manifold [Chaine, 2003] Satisfy our requirements Arbitrary number of connected components Handle points off shape boundary

Reconstruction Based on evolving pseudo-manifold [Chaine, 2003] Satisfy our requirements Arbitrary number of connected components Handle points off shape boundary Interactive (5k points per second)

2D reconstruction Start: pseudo-curve lies on oriented edges of Delaunay triangulation

2D reconstruction During: pseudo-curve evolves as long as oriented Gabriel criterion is not met

2D reconstruction Stop: topologically consistent set of oriented edges

Sampling and Depth Adaptive sampling Displacement map Pencil and brush data in color buffer Color buffer

Sampling and Depth Adaptive sampling Displacement map Approximate disp. map sampled at existing vertices

Sampling and Depth Adaptive sampling Displacement map (D) Vertex-Sampled disp. map (V) Error map E = 1 – ABS(D – V) Arbitrary error value

Sampling and Depth Adaptive sampling Displacement map Approximate disp. map Error map Sampling [Alliez, 2002]

Sampling and Depth Adaptive sampling Depth inference Identify surface vertices Vertices ID buffer

Sampling and Depth Adaptive sampling Depth inference Identify surface vertices Assign depth values Depth buffer

Sampling and Depth Adaptive sampling Depth inference Identify surface vertices Assign depth values Infer depth values from existing surface by depth propagation

Tool Interface Hole marks Comic books production Hole marks Stone #3 (Avalon Studios)

Tool Interface Hole marks Comic books production Our system Hole mark

Tool Interface Video: Basic interface

Tool Interface Blobbing Drawing White shading Distance field Height field Surface

Tool Interface Depth modes (chosen by menu) Modeling “at depth” Depth inference Frisket mode

Video Modeling a tree Paper sketch 3D model obtained with Relief

Results Models (1k to 4k points)

Discussion Intuitive shading convention

Discussion Intuitive shading convention Problems with drawing metaphor No continuous visual feedback Provide two modes

Discussion Intuitive shading convention Problems with drawing metaphor No continuous visual feedback Difficult to obtain continuous shading Provide higher-level drawing tools

Conclusion Modeling by drawing, but imprecise

Conclusion Modeling by drawing, but imprecise Future work Speedup with local 3D reconstruction

Conclusion Modeling by drawing, but imprecise Future work Speedup with local 3D reconstruction Improve depth inference

Conclusion Modeling by drawing, but imprecise Future work Speedup with local 3D reconstruction Improve depth inference Image-space and object-space sampling

Acknowledgements This work has been performed while the first author was a visiting research fellow at Princeton University, supported by an INRIA post-doctoral fellowship. Many people have indirectly contributed to it. We would like to thank: Adam Finkelstein, Szymon Rusinkiewicz, Jason Lawrence, Pierre Alliez, Mariette Yvinec, Laurence Boissieux, Laure Heïgéas, Laks Raghupathi, Olivier Cuisenaire, Bingfeng Zhou.

Relief: A Modeling By Drawing Tool

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Relief: A Modeling By Drawing Tool