1. Introduction and Graphics Pipeline Advanced Multimedia Technology: Computer Graphics Yung-Yu Chuang 2005/12/07 with slides by Brian Curless, Zoran Popovic, Robin Chen and Doug James

2. Introduction Instructor: Yung-Yu Chuang ( 莊永裕 ) E-mail: cyy@csie.ntu.edu.tw Office: CSIE 527 Web: –http://www.csie.ntu.edu.tw/~cyy/amt/

3. What is Computer Graphics ? Definition –the pictorial synthesis of real or imaginary objects from their computer-based models descriptionsimages descriptionsComputer Graphics imagesComputer VisionImage Processing OUTPUT INPUT

4. Computer graphics Create a 2D image/animation of a 3D world

5. Computer graphics modelingrendering animation

6. Applications Movies Interactive entertainment Industrial design Architecture Culture heritage

7. Animation production pipeline storytext treatment storyboard voice storyreallook and feel

8. Animation production pipeline layout animation shading/lighting modeling/articulation renderingfinal touch

9. Scan converting lines A scan-converted line showing intensified pixels as black circles

10. The basic incremental algorithm (x i,Round(y i )) (xi,yi)(xi,yi) (x i +1,y i +m) (x i +1,Round(y i +m)) Desired line

11. The basic incremental algorithm void Line (int x0, int y0, int x1, int y1, value) { int x; float dy, dx, y, m; dy=y1-y0; dx=x1-x0; m=dy/dx; y=y0; for (x=x0; x<=x1; x++) { WritePixel (x, (int)floor(y+0.5), value); y+=m; }

12. Filling Polygons 2468101214 2 4 6 8 10 12 A B C D E F a d b c Scan line

13. Filling Polygons Span extrema Other pixels in the span

14. Filling Polygons 1.find the intersections of the scan line with all edges of the polygon 2.sort the intersections by increasing x coordinate 3.fill in all pixels between pairs of intersections that lie interior to the polygon

15. Transformations

16. Representation

18. 2D transformations

19. Identity

20. Scaling

22. Reflection

23. Shearing

24. Transformation of a unit square

26. Rotation

27. Limitations of a 2X2 matrix Scaling Rotation Reflection Shearing What do we miss?

28. Homogeneous coordinate

29. Translation

30. 3D scaling

31. 3D translation

32. 3D rotation

33. 3D shearing

34. Graphics pipeline

36. 3D synthetic camera model

37. Imaging with the synthetic camera

38. Specifying a viewer

39. Projections

40. Parallel and perspective projections orthographic perspective

41. Orthographic transformation

42. Perspective projection

43. Perspective transform

44. Visibility Algorithms Painter’s algorithm Ray casting Z-buffer Binary space partitioning

45. Ray casting

46. Z-buffer algorithm

49. Binary space partition

50. BSP tree

51. BSP tree construction

52. BSP tree display

53. Back face culling