•
Engineering 1182
Orthographic Projection Basics
Chapter 10 of Text
College of Engineering
Engineering Education Innovation Center
•
Engineering 1182
Objectives
• Discuss the principles of orthogonal
projection
• Show how and why orthogonal projection
is used to create multiple views of an
object for formal engineering drawings
• Create a multiview drawing from a 3-D
object
 Note: The terms orthogonal and orthographic are used to refer to the
same drawing type.
•
Engineering 1182
Why Orthographic Drawings?
• The best way to communicate what an object
looks like is to show someone an image.
• Isometric sketches distort the features of an
object and may lead to misinterpretation.
• Objects must be represented in a way that
prevents misinterpretation.
• Multiview drawings show how an object looks
from multiple angles.
• Multiviews help to prevent any miscommunications that may happen when
looking at only isometric pictorials.
•
Engineering 1182
Orthographic Projections
• Orthographic projections are another way of
representing a 3D object in 2D space.
• In an orthographic projection, the object is
projected perpendicularly onto a viewing plane.
• By using a multiview drawing, we can eliminate
misinterpretations that isometric views alone
allow.
•
Orthographic Projections
• When drawing an
orthographic multiview, it
sometimes helps to
visualize the object inside
of a glass box.
• Imagine that the object is
projected on to each
surface of the glass box.
• The box is then unfolded
to form the multiview
drawing.
Engineering 1182
•
Engineering 1182
How Many Views Do We Need?
• Just projecting one view of a surface isn’t
enough to completely describe the object
This single
view can be
interpreted in
at least 6
different ways!
• To completely describe the object multiple views
are shown.
• Generally, the front, top, and right side are
sufficient to fully represent an object.
•
Engineering 1182
Orthographic Projection
• Use your snap cubes to build the following
object.
• Look at if from the front, right, and top
sides.
Top
 Note: These
are the 3 views
associated with
the object you
just built.
Top
2
1
Front
2
Right
CLICK
Front
Right
•
Engineering 1182
Orthographic Projections
• Typically, the front, top, and right side
views are sufficient to fully describe an
Top
object.
Top
Front
Right
•
Engineering 1182
View Alignments
Depth
B
B
A
A
B
Height
B
Height
– Top: width and depth
– Front: height and width
– Right side: height and depth
Width
Height
• In orthographic
projections, the views are
aligned such that each
point on the object is lined
up with itself all three
views.
• Each view shows two
dimensions
A
A
Width
Depth
CLICK
•
Engineering 1182
Orthographic Projections
• Use this time and your snap cubes to
practice building objects and sketching
orthographic projections.
• In class assignment