Illumination and Color in Computer Generated Imagery

In a very broad sense the historical development of computer graphics can be considered in three phases, each a giant step down the road towards "realistic" computer generated images. The first, during the late 1960's and early 1970's, can perhaps be characterized as the "wire frame" era. Basically pictures were composed of lines. Considerable em­ phasis was placed on "real time" interactive manipulation of the model. As models became more complex and as raster technology developed, eliminating