Perspective camera projection projects points onto the image plane along lines that emanate from a single point, called the center of projection. This means that an object has a smaller projection when it is far away from the center of projection and a larger projection when it is closer.
Perspective Projection describes the mapping from 3D points in the world as they are seen from of a pinhole camera, to 2D points on a viewport.
At perspective projection the viewing volume is a frustum (a truncated pyramid), where the top of the pyramid is the viewing position.
