## Diagonals In Singlepoint Perspective

perspective is shown below. Although we do not need ail the diagonals for purposes of measurement, we should know how to choose the ones we need.

It is very important to understand what is meant by a single-point perspective and two-point perspective and how the planes and their diagonals operate in each. The basic plan for single-point

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Single-point perspective exists when the base lines of the objects or planes in the picture are parallel to the horizon and at right angles to the line of vision. This means that the objects we are looking at arc straight in front of us, not at an oblique angle. Obviously lines parallel to the horizon cannot converge to a vanishing point and therefore have none. In single-point perspective there is only one main vanish

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ing point for all receding parallel planes. It is usually located at or near the middle of the horizon. However, since the diagonals of those planes arc oblique lines, they vanish in two points. Diagonals of horizontal planes vanish on the horizon. Diagonals of vertical planes vanish in a vertical line drawn through the main vanishing point.

DIAGONALS IN TWO-FUll\i rßnjr^.i.w drawing below, while it appears to be com-Ated, is simple when you understand it. We e divided a block into sections of four units . side and carried all the diagonals to their proper vanishing points. This is seldom necessary, but it illustrates the basic plan for diagonals in two-point perspective, and is important to know.

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The vanishing point of the diagonals of the horizontal planes is located on the horizon. What is true of diagonals on vertical planes also applies to inclined planes, as we learn later, for their vanishing points also fall on a vertical line through the vanishing points of the vertical planes. It is necessary to study the drawing carefully to locate the diagonals of any particular section. Try drawing this.

### EQUAL SPACING OF SOLIDS IN PERSPECTIVE

By the same method of measuring depth by means of diagonals we can also repeat a solid block, as shown below. This is valuable in drawing buildings of repeating dimensions or any row of objects that arc constructed within equal blocks. Remember that all objects can be drawn within blocks.

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