Vanishing Point - Viewing Transformations

This point is that point at those parallel lines shows to converge and vanish. A practical illustration is a long straight railroad track.

To demonstrate this idea, consider the Figure 17 that appears a perspective transformation onto z=0 plane. The Figure17 appears a Projected line A*B* of specified line AB parallel to the z-axis. The center of projection is at (0,0,-d) and z=0 be the projection plane.

Identify the perspective transformation of the point at infinity on the +z-axis, that is:

Hence, the ordinary coordinates of a point (x',y',z',1)=(0,0,0,1), consequent to the transformed point at infinity upon the z-axis, is here a finite point. This implies that the whole semi-infinite positive space (0<=z<=∞) is transformed to the finite +ive half space 0<=z'<=d.