ORTHOGRAPHIC PROJECTION
• Orthographic
projection is the
organization of
multiple views of an
object. In order to
fully and accurately
represent the object,
more than one view is
typically required.
Principal Views of an Object
• All orthographic
projections are
composed of six
sides or planes of
projection. All six
views are not
necessary to
describe the object.
Perpendicular Projection to
Each Face
• The lines of the
object are
projected
perpendicular to
the face to create
each view.
Each View Provides Two
Measurements
• a. Top and Bottom
views show DEPTH
and WIDTH.
• b. Left and Right
views show HEIGHT
and DEPTH
• c. Front and Rear
views show HEIGHT
and WIDTH.
Measurement Transfer
Between Views
• The mitre line
(drawn at a 45°
angle) is used
to transfer depth
measurements
between the top
and right side
(or left side)
views.
Normal Plane
• Normal Planes
will appear as
an edge in two
views and a true
sized plan in the
remaining view
when using
three views such
as a top, front
and right side.
Inclined Plane
• Inclined Planes
will appear as
an edge view in
only one of the
three views.
The inclined
plane will
appear as a
rectangular
surface in the
other two views.
Oblique Planes
• Oblique Planes will
not appear as an
edge view in any of
the six views since
they are not
parallel or
perpendicular to
the projection
planes.
• They always
appear as a “plane”
and have the same
number of corners
in each of the six
views.
Curved Surfaces
• A cylinder
will appear
as a circle
in one view
and a
rectangular
shape the
other two
views.
Axis and Center Lines
• The axis appears
where the
cylinder appears
rectangular.
• Center marks are
used to identify
the center of the
cylinder where it
appears circular.