Environment (or Reflection) Mapping
Place your scene inside a cube
Paint images on the faces of the cube to
make a background image that surrounds
your objects. Could be clouds,
Use the cube to illuminate the scene inside it
During the shading calculation:
- Bounce a ray from the viewer off the object (at point P)
- Intersect the ray with the environment map (the cube), at point E
- Get the environment map’s color at E and illuminate P as if there were a virtual light source at position E
- You see an image of the environment reflected on shiny surfaces
Very widely used as an alternative to real ray tracing