Q3Computer Graphics and Multimedia
Question
4 marks
Explain the concept of 3D viewing pipeline.
Answer
The 3D viewing pipeline transforms world-space objects through a sequence of stages — model transform, view transform, projection, clipping, and viewport mapping — to produce a 2D screen image.
The 3D viewing pipeline (also called the graphics rendering pipeline) is the sequence of mathematical transformations that converts 3D scene objects into a 2D screen image.
- 1. Modeling Transform: Transform objects from local/object space to world space using model matrix (translation, rotation, scaling of each object).
- 2. View Transform (Camera Transform): Transform from world space to camera/eye space using the view matrix. The camera is placed at origin looking down -Z axis.
- 3. Projection Transform: Transform from 3D eye space to 2D clip space. Two types: Perspective projection (objects farther appear smaller, realistic) and Orthographic/Parallel projection (no foreshortening, used in CAD/engineering).
- 4. Clipping: Remove primitives or portions outside the view frustum (6 clipping planes for perspective).
- 5. Perspective Division: Divide by w to obtain Normalized Device Coordinates (NDC) in [-1,1]³.
- 6. Viewport Transform: Map NDC to screen pixel coordinates for final display.