1. RAY TRACING

2. RAY CASTING This method is used for determining visible surfaces.
In this method a ray is sent out from each pixel position to locate surface intersections for object modelling.

3. Ray Tracing
In ray tracing instead of merely looking for the visible surfaces for each pixel position ,we continue to bounce the ray around the scene.
This provides a simple technique for obtaining Global Reflection and transmission effects.

4. Ray Tracing Algorithm This provides: Visible surface detection
Shadow effects
Transparency
Multiple light source illumination
This algorithm is developed to produce photorealistic displays(for shiny objects require
considerable computation time to generate).

5. Basic Ray Tracing Algorithm
pixel screen

6. Rat Racing Algorithm
We first set coordinate system with pixel positions in xy plane.
We then determine a ray path passes through the center of each screen- pixel position.
Illumination effects accumulated along this ray path are then assigned to the pixel.
We determine the contributions to a particular pixel by tracing a light path backward from the pixel to the scene.

7. For each pixel ray, we test each surface in the scene to determine if it is intersected by a ray.
If a surface is intersected, we calculate the distance from the pixel to the surface-intersection point.
The smallest calculated intersection distance identifies the visible surface for that pixel.