1. A volumetric pre-clipping method for minimizing sample points processed through a volume rendering system for rendering a volume data set on a 2D graphics display of a computer system, said method comprising the steps of: (a) projecting a volume data set onto an image plane, said image plane having a plurality of pixels, to create a projection of said volume data set on said image plane, comprising the steps of (a1) converting each of the bounding vertices of said volume data set to homogeneous coordinates, (a2) transforming each of said bounding vertices of said volume data set from a source space containing said volume data set to a view space by multiplying each of said homogeneous coordinates of each of said bounding vertices by an orthographic transformation matrix, yielding transformed bounding vertices in said view space; (a3) determining a view vector in said view space, (a4) projecting each of said transformed bounding vertices onto a view plane in said view space through a plurality of rays parallel to said view vector, wherein one of each of said plurality of rays passes through one of each of said transformed bounding vertices, and further wherein said view plane has a plurality of pixels, (a5) transforming said view vector from said view space to said source space by multiplying said view vector by an inverse orthographic transformation matrix yielding a transformed view vector in said source space, and (a6) transforming said plurality of pixels on said view plane in said view space to said image plane in said source space by multiplying each of said plurality of pixels by said inverse orthographic transformation matrix yielding a transformed plurality of pixels in said source space, wherein said projection of said volume data set on said image plane is created; (b) casting a ray from each of said plurality of pixels, wherein each said ray has a plurality of sample points, to create a plurality of rays; (c) clipping all of said plurality of rays cast from pixels that are located outside of said projection of said volume data set on said image plane; and (d) processing, through a volume rendering system, said plurality of sample points located on each ray cast from pixels that are located inside of said projection of said volume data set on said image plane.