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Drawing for Illustration and Annotation in 3D

Drawing for Illustration and Annotation in 3D. David Bourguignon*, Marie-Paule Cani* and George Drettakis** *i MAGIS, INRIA Rhône-Alpes, France **REVES, INRIA Sophia-Antipolis, France. Human heart. Motivation. Drawing Scene complexity in an effective manner Indication of uncertainty

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Drawing for Illustration and Annotation in 3D

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  1. Drawing for Illustration andAnnotation in 3D David Bourguignon*, Marie-Paule Cani* and George Drettakis** *iMAGIS, INRIARhône-Alpes, France **REVES, INRIA Sophia-Antipolis, France

  2. Human heart Motivation • Drawing • Scene complexity in an effective manner • Indication of uncertainty • Limitation to single viewpoint • Applications • Fine arts • Teaching • Early stages of design

  3. Motivation • Goal: drawing in 3D • Augment strokes to true 3D entities • Free-form drawing • Annotation of existing 3D models • Many viewpoints • Problems to be solved • Silhouette stroke modeling • Silhouette stroke rendering from different viewpoints Eye Back

  4. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  5. Previous Work [Pugh, 1992] [Akeo et al., 1994] Specify hidden parts by hand 2D drawing is converted to 3D

  6. Previous Work [Lipson and Shpitalni, 1996] [Eggli et al., 1997] No free-form drawing Limited number of primitives

  7. Previous Work [Cohen et al., 1999] [Tolba et al., 1999] 3D curves design, no drawing 2D drawings reprojected, no visibility changes

  8. Previous Work [Zeleznik et al., 1996] [Igarashi et al., 1999] Closed strokes only Limited to a given gestural interface

  9. Previous Work [Cohen et al., 2000] Drawing modes adapted to landscaping only, no 3D model reconstruction in billboard mode

  10. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  11. Our Approach • Strokes • 2D drawing on the screen plane • Line stroke for 1D details • Silhouette stroke for view-dependent information • Problems to be solved • Inferring local surface from silhouette • Representing uncertainty • Managing occlusions Silhouette stroke Line stroke (3D spline)

  12. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  13. Silhouette Stroke – Modeling • Infer local surface • Fit Bézier curve to 2D user input • Evaluate local curvature • Process curvature vectors • Clamp relatively to inflexion points • Set consistent in/out orientation

  14. Silhouette Stroke – Modeling • Infer local surface • Fit Bézier curve to 2D user input • Evaluate local curvature • Process curvature vectors • Clamp relatively to inflexion points • Set consistent in/out orientation

  15. Silhouette Stroke – Modeling • Infer local surface • Fit Bézier curve to 2D user input • Evaluate local curvature • Process curvature vectors • Clamp relatively to inflexion points • Set consistent in/out orientation

  16. Silhouette Stroke – Modeling • Infer local surface • 3D circles from vectors of curvature • Local Bézier surface

  17. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  18. Silhouette Stroke – Rendering • New silhouette from new viewpoint • Efficient silhouette approximation using clipping planes • Good for local surfaces associated with strokes

  19. Silhouette Stroke – Rendering • Represent uncertainty • Use stroke texture • Color stroke as desired Front (original view) Side (30°) Side (90°) Stroke alpha texture

  20. Silhouette Stroke – Rendering • Manage occlusion • Use occluder texture for soft occlusion • Various drawing styles Occluder alpha texture

  21. Silhouette Stroke – Rendering • Multipass algorithm (Previously render scene and line strokes) • First pass: Rendering silhouette strokes • With stroke texture • With stroke color • Second pass: Soft occlusion by local surfaces (set depth) • With occluder texture • Third pass: Soft occlusion by local surfaces (achieve blend) • With occluder texture • With occluder color

  22. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  23. Interface for Drawing • Two types of strokes • Line stroke • Silhouette stroke • Two drawing modes • In empty space • Relatively to other objects On one object Between two objects

  24. Overview • Previous work • Contributions • Silhouette stroke modeling • Silhouette stroke rendering • Interface for drawing • Results

  25. Applications • Illustration in 3D

  26. Applications • Annotation of a 3D scene

  27. Applications • "Guided design"

  28. Video

  29. Conclusion • System for drawing in 3D • View-dependent strokes with occlusion • Useful for drawing simple scenes in 3D • Useful for annotations • Future work • Handling tubular objects • Real world test: using it to teach anatomy

  30. Acknowledgements • Eric Ferley for feedback throughout the project • Laurence Boissieux for creating some of the drawings, Marc Pont for help with models • Frédo Durand for advice on the paper iMAGIS is a joint project of CNRS, INPG, INRIA and UJF

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