Vanishing point to the axis which is cut by this image plane will have images that meet at a single vanishing point. Lines parallel to the other two axes will not form vanishing points as they are parallel to the image plane. This is one-point perspective. Similarly, when the image plane intersects two world-coordinate axes, lines parallel to those planes will meet form two vanishing points in the picture plane. This is called two-point perspective. In three-point perspective the image plane intersects the , , and axes and therefore lines parallel to these axes intersect, resulting in three different vanishing points. The
Radiant (meteor shower) seen from the perspective of the observer, who views a two-dimensional projection against the sky. The geometric effect is identical to crepuscular rays, where parallel sunbeams appear to converge. A meteor that does not point back to the known radiant for a given shower is known as a "sporadic" and is not considered part of that shower. Shower meteors may appear a short time before the radiant has risen in observer's eastern sky. The radiant in such cases is above the horizon at the meteor's altitude. During the active period of most showers, the radiant moves nearly one degree eastwards,