Orthographic Projections, ContinuedCircles, arcs,and ellipsesCircles, arcs, and ellipses do not appear in true size or shape in an isometricdrawing or projection because all surfaces of the projected object are angledtoward the plane of projection. To draw circles, arcs, and ellipses inisometric drawings and projections, you must use the offset measurement orfour-center method. Make sure to draw enough points to accurately fix thepath of the curve. The more points plotted, the greater the accuracy. Onceyou plot the points, lightly freehand sketch the curve and darken it with theaid of an irregular or french curve.To draw circles, arcs, or ellipses by plotting a series of points, use this table:StepAction1Draw randomly spaced parallel lines across a circle projected intrue size and shape on the plane of projection. To increaseaccuracy, plot more points using more parallel lines.2Transfer these lines from the circle to the isometric drawing orprojection with a pair of dividers. To locate points in objects withsome width, vertically extend the points a distance equal to thewidth of the object. Some of these points will appear as hiddenpoints and lines.3Draw the final ellipse freehand and darken it with an irregular orfrench curve.Continued on next page6-21