1. GVE, Hallym University, Chang Geun Song Ph.D. 1 Chap2. 3D Graphics Fundamentals 한림대학교 컴퓨터공학부 송 창근

2. GVE, Hallym University, Chang Geun Song Ph.D. 2 What you’ll learn in this chapter 4 How the eyes perceive three dimensions 4 How a 2D image can have the appearance of 3D 4 How Cartesian coord specify object position 4 What a clipping volume is 4 How viewports affect image dimensions

3. GVE, Hallym University, Chang Geun Song Ph.D. 3 What you’ll learn in this chapter 4 How 3D objects are built from 2D primitives 4 How to work with Orthographics and Perspective Projections

4. GVE, Hallym University, Chang Geun Song Ph.D. 4 3D Perception 4 양쪽눈은 물체에 대해서 약간의 서로 다른 이미지를 바라본다. 4 물체와 거리가 멀어지면  가 작 아진다. 반대로 거리가 가까와지 면  의 값이 커진다. 4 예 ) Viewmaster 혹은 3D 영화 4 거리 측정 실험. ( 외눈, 양안 사용 )

5. GVE, Hallym University, Chang Geun Song Ph.D. 5 2D + Perspective = 3D

6. GVE, Hallym University, Chang Geun Song Ph.D. 6 2D + Perspective = 3D Perspective 가까이 있는 물체가 멀리 있는 물체보다 커 보이는 현상 Perspective + Color changes, textures, lighting, and variations of color intensity — 3D image perception Perspective 만으로도 3 차원 인식 가능 예 ) Fig. 2-2, Wireframe cube, 단점은 2 가지 형태로 보 임.

7. GVE, Hallym University, Chang Geun Song Ph.D. 7 Fig. 2-2 전면과 후면을 구별하기 힘듬 Fig. 2-2 가 solid 이면 후면은 전면에 의해 가려 지 므로 후면을 볼 수 없다. 따라서 전면과 후면을 혼동 하지 않을 수 있음. Fig. 2-3, Hidden lines are removed. Hidden Line Removal

8. GVE, Hallym University, Chang Geun Song Ph.D. 8 Colors and Shading

9. GVE, Hallym University, Chang Geun Song Ph.D. 9 Colors and Shading Fig. 2-4 은 실제 물건 같지가 않다. 육방체의 모든 면 이 같은 색깔이다. 현실감이 있게 보이도록 원근감을 갖도록 하려면 보이는 3 개의 면을 서로 다른 색으로 그리거나 보이는 3 개의 면을 같은 색으로 하되 빛의 조도 에 따라서 shading 을 갖도록 한다. (Fig. 2-5)

10. GVE, Hallym University, Chang Geun Song Ph.D. 10 Light and Shadows 4 빛의 효과 (Lighting) 4 It causes a surface of a uniform color to appear shaded (illuminated) 4 It cast a shadow 4 Two source of light –Ambient : undirected, –Directional Point source, Lamp

11. GVE, Hallym University, Chang Geun Song Ph.D. 11 Coordinate Systems How to draw 3D objects on the screen (2D)? Using output primitives such as points, lines, polygons etc. Position : (row, column) Standard VGA 640 pixels from left to right 480 pixels from top to bottom

12. GVE, Hallym University, Chang Geun Song Ph.D. 12 2D Cartesian Coordinates How to map the true coordinate to window coord.

13. GVE, Hallym University, Chang Geun Song Ph.D. 13 Coordinate Clipping Two Clipping Areas : 0  x  150, 0  y  100 -75  x  75, -50  y  50 ( 참고사항 )Windows(Microsoft) : for positive y to move down from top to bottom of the window

14. GVE, Hallym University, Chang Geun Song Ph.D. 14 Viewports, Your Window to 3D Fig. 2-9 A viewport defined as twice the size of the clipping area

15. GVE, Hallym University, Chang Geun Song Ph.D. 15 Viewports, Your Window to 3D Fig. 2-10 A viewport defined as the same dimensions as the clipping area.

16. GVE, Hallym University, Chang Geun Song Ph.D. 16 Viewports, Your Window to 3D Viewport : the region within the window’s client area that will be used for drawing the clipping area Fig. 2-9 : Each increment in the logical coordinate system would be matched by 2 increments in the physical coordinate system of the window (pixel) Fig. 2-10 : shows a viewport that matches the clipping area. What if we set the viewport to be larger than the window client area?

17. GVE, Hallym University, Chang Geun Song Ph.D. 17 Drawing Primitives Primitives : points, lines, and polygons (a flat, multisided shape)

18. GVE, Hallym University, Chang Geun Song Ph.D. 18 3D Cartesian Coordinates Z-axis (new axis), Right-Handed System(RHS)

19. GVE, Hallym University, Chang Geun Song Ph.D. 19 Projections, The Essence of 3D Fig. 2-12. A 3D image projected onto a 2D surface

20. GVE, Hallym University, Chang Geun Song Ph.D. 20 Projections, The Essence of 3D Projection : It is like tracing the outlines of some object behind a piece of glass with black marker. Clipping Volume : you want to be displayed in your window.

21. GVE, Hallym University, Chang Geun Song Ph.D. 21 Orthographic Projection Orthographic parallel projection  rectangular clipping volume Architectural design or CAD

22. GVE, Hallym University, Chang Geun Song Ph.D. 22 Perspective Projection Viewing volume : like a pyramid with the top shaved off Frustum More realistic, simulation, 3D animaton