Introduction to
Perspective Projection
Perspective Projection
Perspective Projection is a geometric
technique used to produce a three-
dimensional graphic image on a plane,
corresponding to what a person
actually sees
Perspective Projection
One point Perspective
Two point Perspective
Auxiliary vanishing points
Perspective Projection
• Parallel lines appear to converge as they recede from the spectator.
• Equal distances appear to get shorter.
• Objects of the same size seem to diminish in size as they recede.
Vanishing point
Perspective Projection
Vanishing Point
Vanishing Point
Horizon Line
The height of the horizon line always corresponds to the height of the spectator’s eye
Terminology
Ground Plane: The plane on which the spectator is standing. The plan of the
object to be drawn lies on it - the object itself may also rest on it
Picture Plane: The transparent plane perpendicular to the ground plane
Ground Line: The line of intersection between the picture plane and the ground
plane
Spectator: The person observing the object (or objects)
Cone of Vision
blind to
right eye
distorted
30° angle 60° angle
cone of vision
distorted
blind to
left eye
Cone of Vision
A 60° cone of vision gives a good perspective view of an object
The axis of the cone is called the centre line of vision
The picture plane is drawn perpendicular to the centre line of vision
Terminology
Horizon Line: The height of the horizon line above the ground line is equal to that
of the spectator’s eye above the ground plane
Vanishing Point: The vanishing point for any line is found on the Picture Plane
and is located by drawing a sight line from the spectator parallel to
that line
The vanishing points for all horizontal lines lie on the horizon line
Terminology
Sight Lines: The straight lines drawn from various points on the object
to the eye of the spectator
The points of intersection of the sight lines with the picture plane
yield the perspective view of the object
Perspective Projection
Work sheet 1
One point perspective
The centre line of vision is perpendicular to a side of the object.
This side and all lines parallel to this side will be parallel to the picture
plane so they do not converge.
Perspective Projection
Work sheet 1
• Parallel lines vanish to the same vanishing point.
• Lines parallel to the picture plane in plan do not
converge.
• If lines are parallel to the horizontal plane then the
vanishing point is on the horizon line.
• The sides touching the picture plane are true
dimensions.
Perspective Projection
Worksheet 2 Two point perspective
Perspective Projection
Work sheets 2,3
• Picture plane perpendicular to centre line of
vision.
• Sets of parallel lines appear to converge to the
same vanishing point.
• The vanishing points for all horizontal lines lie on
the horizon line.
• The edge touching the picture plane is a true
height.
Perspective Projection
• Work sheet 4
Perspective Projection
Work sheet 4,5,6
Height line
• When the edge of the object is not touching the picture plane a height line
must be established on the picture plane.
Identify a surface that contains necessary heights. Extend the surface to
intersect the picture plane i.e. extend the surface parallel to its vanishing
parallel. The elevation of the line of intersection gives the necessary
heights .
Height line
Auxiliary Vanishing points
Parallel lines vanish to the same vanishing point
The vanishing point for any line is found on the Picture Plane and is located by
drawing a sight line from the spectator parallel to that line
The sight line for sloping lines intersects the PP at a height above or below the
vanishing points
Perspective Projection
Work sheets 9,10
Perspective Projection
Worksheet 9
Perspective Projection
• The picture plane can be placed in front of, behind, or even through an
object.
• The perspective view is drawn by projecting the sight lines from the
spectator through the points of the object onto the picture plane.
• If the picture plane is located behind the object the perspective view is
larger than the object.
Perspective Projection
Work sheets 11,12,13,14
• True heights can be measured where the object is intersected by
the picture plane.
• The closer to the spectator the picture plane is located the smaller
the drawing, the further away the larger the drawing.
• If the picture plane is located between the object and the spectator,
the resulting perspective view is smaller than the object.
• If the picture plane is positioned behind the object, relative to the
spectator the resulting perspective view is larger than the object.
