---
tag: YHKSDF59HK
kind: concept
name: Perspective projection
msc: [51N05, 51N15, 68U05]
sources:
  - url: https://en.wikipedia.org/wiki/Perspective_(graphical)
---

## Summary

A perspective projection maps the points of space onto a picture plane along the lines through a fixed centre, the eye.
It is the geometry behind realistic drawing, photography and 3D computer graphics.
Straight lines stay straight, but parallel lines that are not parallel to the picture plane converge to a common vanishing point.
In projective terms it is a central projection, and its restriction to a plane is a [[perspectivity|QTZWZR1KWQ]] between planes.

## Explanations

### L1 human

Put a glass window between your eye and a street, and trace on the glass what you see.
Each point of the street is drawn where the ray from it to your eye crosses the glass.
The two edges of a straight road are parallel, but on the glass they run together toward a single point on the horizon.
Far objects come out small and near objects large, which is what makes the picture look real.