Ray Tracing v.s. Rasterization
Ray Tracing was developed as one approach to modelling the properties of global illumination
- Global models include incident light that arrives from other surfaces, and lighting effects
that account for global scene geometry. Such effects include:
- Shadows
- Secondary illumination (such as color bleeding)
- Reflections of other objects, i.e. mirrors
Basic Ideas:
- Cast a ray from the eye of the camera through the pixel, and find the first surface hit by
the ray
- Determine the surface radiance at the surface intersection with a combination of local
and global models
- To estimate the global component, cast rays from the surface point to possible incident
directions to determine how much light comes from each direction. This leads to a
recursive form for tracing paths of light backwards from the surface to the light sources
Computational Issues:
- Form rays
- Find ray intersections with objects
- Find closest object intersections
- Find surface normals at object intersection
- Evaluate reflectance models at the intersection
Ray Tracing:
- Tracing the path taken by a ray of light through the scene
- Rays are casted to each pixel. They are reflected, refracted, absorbed whenever they intersect objects
Procedure: