1. Points, Lines, and Planes

2. Basic Geometric Elements
Points, Lines, and Planes Individually Represented

3. Basic Geometric Elements
Normal Edges
A normal edge is a line that is perpendicular to a plane of projection.
It appears as a point on the plane of projection to which it is perpendicular.
It appears as a true length line on the planes of projection to which it is parallel.

4. Basic Geometric Elements
Normal Edges
A normal edge is a line that is perpendicular to a plane of projection. It appears as a point on the plane of projection to which it is perpendicular and as a true length line on adjacent planes.

5. Basic Geometric Elements
Inclined Edges
An inclined edge is a line that is parallel to a plane of projection but inclined to adjacent planes.
An inclined edge appears true length on the plane to which it is parallel and foreshortened on adjacent planes.

6. Basic Geometric Elements
Inclined Edges
The true length view of an inclined line is always inclined while the foreshortened views are either vertical or horizontal lines.

7. Basic Geometric Elements
Oblique Edges
An oblique edge is a plane that is oblique to all planes of projection.
Since it is not perpendicular to any plane it cannot appear as a point in any view.
Since it is not parallel to any plane it cannot appear true length in any view.
An oblique edge appears foreshortened and in an inclined position in every view.

8. Basic Geometric Elements
Example of Oblique Edges

9. Basic Geometric Elements
Views of Points, Lines and Planes

10. Basic Geometric Elements
Views of Points and Lines

11. Intersecting Lines

12. Nonintersecting Lines

13. Visibility of Nonintersecting Lines

14. Geometric Constructions
Solids
Solids bounded by plane surfaces are called polyhedra.
The surfaces are called faces.
If the faces are equal regular polygons the solids are called regular polyhedra.

15. Visibility of Nonintersecting lines
Visibility of Nonintersecting lines of a Tetrahedron

16. True Length of an Oblique Line

17. True Length of an Oblique Line
True Length by
Revolution

18. Point View of a Line

19. Straight Line in a Plane

20. Point in a Plane

21. Edge View of a Plane

22. Piercing Point
Piercing Point – Edge View Method

23. Piercing Point
Piercing Point – Cutting Plane Method

24. Piercing Point
Piercing Point – Cutting
Plane Method