Last reviewed 16 Sept 2026 · 8 min read
Perspective projection
A perspective represents an object as it appears to the eye from a particular point. Projectors (visual rays) from all points of the object converge at the observer's eye (station point) and pierce a transparent picture plane; the pierce points form the perspective.
Characteristics
- Objects farther from the observer appear smaller.
- Parallel lines (not parallel to the picture plane) appear to converge towards a vanishing point.
- Lines parallel to the picture plane remain parallel (and vertical lines remain vertical in one- and two-point perspectives).
- Objects touching the picture plane appear in true size; objects behind it appear smaller, in front larger.
- Gives a realistic view but not true measurements — used for architectural presentation, advertising and client communication.
Terminology
| Term | Meaning |
|---|---|
| Station point (SP) | Position of the observer's eye |
| Picture plane (PP) | Transparent vertical plane between observer and object on which the perspective is drawn |
| Ground plane (GP) | Horizontal plane on which the object and observer stand |
| Ground line (GL) | Line of intersection of PP and GP |
| Horizon plane / horizon line (HL) | Horizontal plane at eye level; its intersection with PP is the horizon line |
| Eye level | Height of SP above GP — distance between GL and HL |
| Centre of vision (CV) | Point where the axis of vision (perpendicular from SP to PP) meets PP — on HL |
| Axis of vision | Line from SP perpendicular to PP |
| Vanishing point (VP) | Point on the horizon line where parallel horizontal lines appear to meet |
| Cone of vision | Cone of rays within which objects appear undistorted — commonly kept within about 30° (up to about 60°) included angle |
Types of perspective
| Type | Position of object relative to PP | Vanishing points | Use |
|---|---|---|---|
| One-point (parallel) perspective | One face parallel to PP | One (at CV) | Interiors, corridors, streets, railway lines |
| Two-point (angular) perspective | Vertical edges parallel to PP; faces inclined to PP | Two on the horizon line | Exterior views of buildings (most common) |
| Three-point (oblique) perspective | No edges parallel to PP (PP inclined) | Three (two on HL, one above or below) | Tall buildings viewed from ground (worm's-eye) or from above (bird's-eye) |
Views by eye level
- Bird's-eye view — horizon line above the object (eye level high) — shows roof and layout.
- Normal (human) eye view — eye level about 1.5–1.7 m above ground.
- Worm's-eye view — horizon line at or below ground level — object appears towering.
Methods of drawing perspective
Visual ray method
- Draw the top view (plan) of the object with the PP (as a line) and SP located.
- Draw the front/side view with GL and HL positions.
- Draw visual rays from SP to each corner in the top view; mark where they pierce PP.
- Project these points down to the perspective area.
- Heights: from points where rays cross PP, combine with visual rays in elevation (from SP elevation to corners) where they cut PP, or use true height lines at points touching PP.
- Join corresponding points.
Vanishing point method
- In the top view, draw lines from SP parallel to the principal horizontal edges of the object until they meet PP — these locate the vanishing points, which are projected onto the horizon line.
- Find a line of true height — a vertical edge lying in the PP (or extended to meet it), where heights are measured true.
- Draw lines from the ends of the true height line to the vanishing points; locate other corners by projecting pierce points (from visual rays) down.
- Complete the object.
This method is faster for buildings with many parallel edges.