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Computer Graphics & 3D Painting

Computer Graphics & 3D Painting. Xia Jiazhi Central South University. Xia Jiazhi. Lecturer at Central South University Received Ph.D. at Nanyang Technological University, Singapore, in 2011 Research: Computer Graphics and Human-Computer Interaction. What is Computer Graphics?.

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Computer Graphics & 3D Painting

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  1. Computer Graphics& 3D Painting Xia Jiazhi Central South University

  2. Xia Jiazhi • Lecturer at Central South University • Received Ph.D. at Nanyang Technological University, Singapore, in 2011 • Research: Computer Graphics and Human-Computer Interaction

  3. What is Computer Graphics?

  4. What is Computer Graphics • A technique to generate digital images from 3D models using computer.

  5. Which one is the real BMW?

  6. Is it Fake or Photo?

  7. The image may cheat us

  8. Why Computer Graphics?

  9. Why computer graphics • About 50% of the brain neurons are associated with vision. • Dominant form of computer output. • Enable scientists (also engineers, doctors, and general users) to observe their simulation and computation. • Computer graphics is application driven! • Movie • Game • Computer-aided design (CAD) • Medical imaging • Computer art • Graphical user interface (GUI) • Scientific visualization

  10. Movies • If you can imagine it, it can be done with computer graphics. • More than one billion dollars on special effects. More and more of these images exist only within the memory of a computer. No end in sight for this trend! • Computer graphics is now as much a part of the video and movie production industry as stuntmen and makeup.

  11. Video Games • Games are the driving force in computer graphics. • Games market is the stimulus for the powerful graphics processors (GPU) Crysis 3 2013 Spacewar 1961 Counter Strike 2005

  12. Computer-Aided Design(CAD) • Today, most mechanical and electronic designs are executed entirely on computer. Increasingly, architectural and product designs are also migrating to the computer. Automated tools are also available that verify tolerances and design constraintsdirectly from CAD designs. • CAD can significantly reduce the design cycles for industrial products, e.g., the mobile phones

  13. Graphical User Interface(GUI)

  14. Visualization

  15. How Computer Graphics Works?

  16. Simulating the Everyday World • Three broad areas: • Modeling(Geometric) = Shape • Animation = Motion/Behavior • Rendering = Appearance

  17. Representing the Shape

  18. Geometric Modeling

  19. Geometric Modeling

  20. Geometric Modeling

  21. Animating the world

  22. Animation

  23. Natural phenomena simulation

  24. Rendering

  25. Rendering • Rendering is the process of generate an image from a scene, which contains geometry, viewpoint, texture and lighting information. It is similar to photography or cinematography. • Simulation of realistic lighting, shadows, atmosphere, color, texture and optical effects such as refraction of light or motion-blur seen on moving objects.

  26. Representing the Surface Details

  27. Texture Maps • How is texture mapped to the surface? • Dimensionality: 1D, 2D, 3D • Texture coordinates (s, t) • Surface parameters (u, v) • How to assign the Surface parameters? • Parameterization!

  28. 3D Painting • Assign colors to vertices directly in a painting interface • WYSIWYG(What You See Is What You Get) system • Painting on self-occluded model • A lot of manual work, even impossible

  29. Start from Reality Model From Jeremy Birn

  30. Start from Reality model From Jeremy Birn Model + illumination

  31. Start from Reality Model From Jeremy Birn Model + illumination Model + illumination + Texture

  32. 3D Painting • An interactive technique for 3D model surface properties editing • 3D model surface properties are required by reconstructing the surface details of the real object • Color • Illumination • Transparency • Normal（bump mapping） • Displacement mapping • ……

  33. The 3D Painting System

  34. The Challenge of 3D Painting • The dimension • 3D interaction + 3D display • 2D interaction interface is still the major method of industry[P. Hanrahan et al. 1990] • Operation • The occlusion is a challenge to interaction even in real world • The Creation skill • General users lack the professional creation skill

  35. 1. Occlusion

  36. Our Method

  37. Depth Layer Layer 1 Layer 2

  38. Depth peeling Layer 1 Layer 2

  39. Region Segmentation Depth Information The pixel adjacent information Region Segmentation Region adjacent information

  40. Layer-aware Interaction

  41. Layer-aware Interaction

  42. A complete painting demo

  43. 2. The difficulty of creation • 3D painting requires professional creation skill

  44. Decal System • Copy+Paste Schmidt et al. 2006

  45. Exponential Map Can only control the center point and the direction

  46. Sketch-based texture mapping • Free control of the texture deformation • More close to painting experience of general users

  47. Sketch-based texture mapping Extended exponential map Texture map

  48. Extended exponential map

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