Oblique Projections, ContinuedReceding linesLines perpendicular to the plane of projection appear in oblique projectiondrawings as parallel inclined lines. These lines appear to recede but never toconverge; hence the name, receding lines.Angles ofreceding linesYou may draw receding lines at any convenient angle. The angle you selectto draw receding lines depends on the shape of the object and the location ofany significant surface features. Use a large angle to draw receding lineswhen you want a better view of the top of an object.Use a small angle whenyou want to show features on the side of an object.Choose angles easilydrawn with 45° and 30°/60° triangles.Length ofreceding linesOblique projections present an unnatural appearance to the eye because thereceding lines do not converge into a vanishing point but remain parallel andseem to diverge in the distance. The length of the receding lines contributesto distortion. Receding lines drawn in full scale give the appearance of beingtoo long and raising the back of the object higher than the top or frontsurface. For this reason, objects with great length should not be drawn in theoblique with the longest dimension perpendicular to the plane of projection.For the object to appear more natural, foreshorten the receding lines.Oblique projections with full scale receding lines are known as cavalierprojections. Drawings where the receding lines are foreshortened by half arereferred to as cabinet projections.Figure 6-4 illustrates the difference in distortion between a cavalier andcabinet projection.Figure 6-4.—Adistorted cavalierprojection andforeshortened cabinetprojection of a cube.Continued on next page6-6
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
