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. Note: These are the 3 views associated with the object you just built. Top Front Right Top 2 1 CLICK Front Right

Orthographic Projections Typically, the front, top, and right side views are sufficient to fully describe an object. Right Top Front Top Need a slide after this one that talks about view alignments 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 Height Width B A B Depth Depth A B B Height Height A A Width Depth CLICK

Orthographic Projections Use this time and your snap cubes to practice building objects and sketching orthographic projections. In class assignment