## Oblique

Figure 4-9 Isometric drawings present the three primary faces of an object equally and at the same angle with the viewing plane.

VIEWING PLĂ„NE

Figure 4-10 Isometric drawings are generally constructed as "wire frames'' showing the construction lines.

Figure 4-10 Isometric drawings are generally constructed as "wire frames'' showing the construction lines.

Figure 4-12 In a plan oblique drawing, the true plane can be rotated at any angle, although the 30-60 degree and 45-45 degree are most popular.

to construct, but the visual distortion caused by parallel lines not appearing to converge to a distant vanishing point gives them a distinctly pictorial effect. Computer software now allows the designer to program in dimensions for width, height, and depth. Then, isometric "wire frames" that show the construction lines can be quickly generated on the screen, as illustrated in Figure 4-10. Hidden or unwanted lines can also be easily turned off or removed from the image.

In dimetric and trimetric drawings, all principal faces are not held at equal angles to the picture plane (Figure 4-11). The dimetric drawing makes two faces equally visible and shortens the third face. The trimetric rotates an object so that all three faces are at different angles to the picture plane.

In both dimetric and trimetric drawings, the scale along one or more of the principal faces is reduced proportionately to emphasize or deemphasize a feature of the object. Both dimetric and trimetric drawings are more time-consuming to construct than isometric drawings, but have the advantage of presenting an object's best features and more closely resembling perspective drawings.

### Oblique Projections

Oblique projections are popular among interior designers. Although there are several types of oblique drawings, the plan oblique and elevation oblique are the most commonly used. In these drawings, the floor plan or elevation serves as the true face on the picture plane, and parallel lines are projected vertically or horizontally at an angle other than 90 degrees from this face. The viewer's lines of sight are parallel, but are not at right angles with the viewing plane (Figure 4-12). Oblique drawings also have the feature that one face of an object is always parallel to the viewing plane and represented in true proportion, such as an elevation or plan view. The parallel lines are sometimes reduced in scale (short-

ened) from true size to reduce the visual distortion. With the use of specialized computer software, these views can be generated or extruded from a plan or elevation view with the click of a mouse.

To produce a plan oblique, the true shaped plan can be rotated to any angle, although the 30/60-degree and 45/45-degree are the most popular. The advantage of the plan oblique is that the building's floor plan can be used directly to generate this kind of drawing. By contrast, isometrics are more time-consuming because of the extra projections and dimensioning required. A floor plan or elevation cannot be used directly to produce an isometric drawing.

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### Responses

• phillip
When do you have to draw oblique figures in architectural drawings?
12 months ago
• Alyx
What are oblique drawings in construction?
5 months ago