Orthographic Projection Basics Chapter 10 of Text
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.
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 mis-communications that may happen when looking at only isometric pictorials.
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.
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.
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 2 1 Front Right CLICK Right Front
Orthographic Projections • Typically, the front, top, and right side views are sufficient to fully describe an object. Top Top Front Right Front Right
View Alignments Width • 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 • Top: width and depth • Front: height and width • Right side: height and depth Width B Height A B Depth Depth A B B Height Height A A Depth Width CLICK
Orthographic Projections • Use this time and your snap cubes to practice building objects and sketching orthographic projections. • In class assignment