Ray Casting -polygon rendering and ray tracing methods

It is a method wherein the surfaces of objects visible to the camera are determined by throwing or say casting rays of light from the viewer in the scene. The concept behind this casting is to shoot rays from the eye, one per pixel and get the closest object blocking the path of such ray - think of an image as a screen-door, along with each square in the screen being a pixel.

It is then the object the eye usually sees by that pixel. By using the material properties and the consequence of the lights in the view, this algorithm can find out the shading of this object. The simple assumption is made when a surface faces a light, then the light will reach such surface and not be blocked or in shadow. The shading of the surface is calculated by using traditional 3-D computer graphics shading models. This type of casting is not a synonym for ray tracing, although can be thought of as an abridged, and considerably faster, version of the ray tracing algorithm. Both images are order algorithms utilized in computer graphics to render 3-dimensional scenes to two dimensional screens by subsequent rays of light from the eye of the observer to a light source. Though ray tracing is as same to ray casting, this may be better consideration of as an extension of ray casting we will discuss such in the next topic in this section.