# Perspective and Illusion

16 17 some perspecTIve basIcs diagonals and inclined planes A few perspective primers are shown on this page, all of which make good exercises for an artist. Start opposite top with the simple square in the centre of the image. It is completely defined from its front line, as its back corners are the intersections of diagonal dashed lines from its front corners to the central and side vanishing points. The next square away from the viewer can be positioned by the same method, and so on. The perspective centre of an object is obtained by drawing its diagonals and noting where they cross. It is useful for correctly positioning doors, windows, roof arches, bellybuttons, belts and noses in paintings and drawings. Circles in perspective are perfect ellipses. To draw them, remember that a circle sits in a square, cuts the diagonals at just over T, and touches the square at points which are given by the perspective centre, and the same is true for the ellipse. Inclined planes, like shadows, use vanishing points exactly above or below the ordinary horizon vanishing points. Below is a clue to using plan and elevation in perspective. using the perspective centre to centrally position an opening or feature within a rectangle vpl vpc vpr using diagonals aligned to left and right vanishing points to give correct depth pc. vps using further vanishing points to align twisted objects and a raised slope vanishing point vps which is directly above its horizontal counterpart vpr vpl below a circle in simple perspective is a perfect ellipse, note it cuts the diagonals into T vpl vpc vpr horizon horizon horizon