- Understanding Solid Objects
- Understanding Sketching Techniques
- 3.1 Technique of Lines
- 3.2 Sketching Straight Lines
- 3.3 Sketching Circles, Arcs, and Ellipses
- 3.4 Maintaining Proportions
- 3.5 One-View Drawings
- 3.6 Pictorial Sketching
- 3.7 Projection Methods
- 3.8 Axonometric Projection
- 3.9 Isometric Projection
- 3.10 Isometric Drawings
- 3.11 Making an Isometric Drawing
- 3.12 Offset Location Measurements
- 3.13 Hidden Lines and Centerlines
- 3.14 Angles in Isometric
- 3.15 Irregular Objects
- 3.16 Curves in Isometric
- 3.17 True Ellipses in Isometric
- 3.18 Orienting Ellipses in Isometric Drawings
- 3.19 Drawing Isometric Cylinders
- 3.20 Screw Threads in Isometric
- 3.21 Arcs in Isometric
- 3.22 spheres in Isometric
- 3.23 Oblique Sketches
- 3.24 Length of Receding Lines
- 3.25 Choice of Position in Oblique Drawings
- 3.26 Ellipses for Oblique Drawings
- 3.27 Angles in Oblique Projection
- 3.28 Sketching Assemblies
- 3.29 Sketching Perspectives
- 3.30 Curves and Circles in Perspective
- 3.31 Shading
- 3.32 Computer Graphics
- 3.33 Drawing on Drawing
- Key Words
- Chapter Summary
- Worksheets
- Review Questions
- Sketching Exercises
This chapter is from the book
This chapter is from the book
This chapter is from the book
3.7 Projection Methods
The four principal types of projection are shown in Figure 3.33. All except the regular multiview projection (Figure 3.33a) are pictorial types, because they show several sides of the object in a single view. In both multiview projection and axonometric projection, the visual rays are parallel to each other and perpendicular to the plane of projection. Both are types of orthographic projection (Figures 3.33a and 3.33b).
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3.33 Four Types of Projection
In oblique projection (Figure 3.33c), the visual rays are parallel to each other but at an angle other than 90° to the plane of projection.
In perspective (Figure 3.33d), the visual rays extend from the observer’s eye, or station point (SP), to all points of the object to form a “cone of rays,” so that the portions of the object that are farther away from the observer appear smaller than the closer portions of the object.