1. Computer Graphics

2. Two File Types:
Vector
&
Raster

3. Example: Line

4. end
Vector
direction
start

5. Vector
length
angle
midpoint
etc…

6. Vectors:
Creates easily defined and manipulated objects, like lines, curves, boxes, cylinders, etc…
Vector data can be in 2D or 3D.
Vector files are relatively small in size.

7. Problem: Not all information is based on objects.
(i.e. photographs and paintings)
No real practical way to experience vector data.
(i.e. monitors and printers use a grid of dots or pixels.)

8. Raster

9. Pixel

10. Raster: Best when used to represent pictures or images.
Raster data is very portable with common, device independent formats (i.e. computer, camera, etc…).
Pixels are easily viewed on a monitor or printed on paper.

11. Problem: Not all information is based on images.
(i.e. lines, curves, boxes, cylinders, etc…)
Difficult to modify.
Limited to 2D.
File sizes can be very large.
Aliasing is a problem

12. Problem:
aliasing

13. Solution
1. anti-aliasing

14. Solution
2. Use a lot of “small” pixels

15. Raster (pixels) vs
Vectors (geometry)

16. OK, So let’s make a wall

17. Pixels?

18. or Geometry?

19. How about a brick wall?

20. Geometry?

21. or Pixels?

22. Geometry: Pros: Fully three-dimensional
Casts shadows, reflections, etc…
Easier to position and modify
Cons:
Takes more time to calculate (render) - Slow
Complex textures hard to model

23. Pixels: Pros: Takes less time to calculate (render) – Fast
Easily represents complex textures
Cons:
Can be difficult to accurately position
Modification requires different software
Usually requires external files (texture maps)

24. Example: Still Image
Usually scrutinized – More detail is required.

25. Example: Still Image
Large images need lots of Pixels, resulting in long calculations, or render times (above image over 1 hour for 3000x2000 pixels).

26. Example: Animation
Individual frames less scrutinized – need less detail.

27. Example: Animation
Smaller images require fewer pixels, thus shorter rendering times per frame (above image 10 minutes per frame). BUT,….

28. Example: Animation
Long animations require many frames (above animation has 2000 frames).

29. Example: Animation
At 10 minutes a frame, entire animation requires 20,000 minutes to complete (about 14 machine days).

30. Example: Video Games
Action and interactivity demands immediate or real-time rendering (times).

31. Example: Video Games
To lower rendering times, game designers use “low polygon modeling” and extensive texture mapping.
Simple geometry + pixels = fast rendering times.