1. Point, Edge, and Surface Tracking
Sections and of Text
I think this stuff is too advanced for this point in time with the students. It should probably be moved back to the part with the missing views.

2. Objectives
Use the principles of orthographic projection to identify points, edges, and surfaces in orthogonal views.

3. Points in Orthographic Projection
When views of an object are projected onto the glass cube and it is unfolded, points will “line up” from one view to the next. B A B C C A B B A C A C
CLICK

4. Edges in Orthographic Projection
Edges on objects are defined by two or more points, so they also project orthographically between views.
Note that sometimes, an edge may appear to be a point, when you are looking directly down the line.
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5. Point and Edge Tracking17 16 15
No.
Front
Top 1
Edge
1-2
8-9 or 17-16 2
Point 3
12 or 13
2-4
9-10 or 16-15 4
3 or 6 12 5
1 or 7 17 6
10-11 or 14-15 7
9-16 13 14 11 12 8 9 10 1 2 3 4
CLICK 7 6 5

6. Surfaces in Orthographic Projection
Surfaces on objects are defined by three or more points, so they also project orthographically between views.
Note that sometimes, a surface may appear to be a line, when you are looking directly down the edge of that surface.
CLICK

7. Surface Tracking Surface No. Front Top 17 16 15 13 14 11 12 8 9 10 1 2
2-3-4 2
Surface 2
3-6
12-13 3
Surface 3
1-2 4
Surface 4
4-5
14-15 5
Surface 5
12-11 or 13-14 6
Surface 6 or 7
Surface 7
1-7
8-17 17 16 15 13 14 11 12 8 9 10 1 2 3 4
CLICK 7 6 5

8. Point, Edge, and Surface Tracking
Use this time to practice sketching orthographic projections of more complex objects. Don’t forget to include hidden lines and centerlines.
In class assignment