8Drawings have a one-point perspective when a single vanishing point (VP) seats on the horizon line. The position of the vanishing point can vary in its horizontal location, but it always stays on the horizon line. Therefore, draw the horizon line first, then determine the VP position on it.
In the image below you see how the road lines converge in a single VP. The right position of converging lines helps you draw with accuracy the exact size of objects receding in space. For instance, the trees’ size on the right changes in accordance with the linear perspective.
We observe such perspective by looking at highway roads, railway tracks, hotel hallways, or even buildings that we see facing us directly. The image of a hallway above shows the position of one VP on a horizon line, and all lines converge in it far in the distance. This helps us draw the exact size and the slant of the hotel’s doors and lights.
http://www.craftsy.com/blog/2015/11/perspective-in-art/
