Local Illumination Model - Polygon Rendering
In this only light that is directly reflected by a light source through a surface to our eyes is observed. No explanation is taken of any light which is incident on the surface after multiple reflections among other surfaces. This is the type of illumination model that is used in most scan-line rendering pipelines. The contribution by the light which goes directly by the light source and is reflected from the surface is termed as a "local illumination model". Thus for a local illumination model, the shading of any surface is independent of the shading of all the other surfaces. The scan line rendering system utilizes the local illumination model.