- Zig, Then Zag (basic perspective principles)
- The Wide and The Narrow (consistency of a curving path)
- Up The Down Roadway (inclines and bridges)
- Over Hill and Dale (conclusion)
ON THE ROAD AGAIN
A road, river, or path that stretches off into the distance can be drawn merely as two lines that meet (at a vanishing point) on the horizon. They are amongst the simplest things to draw in perspective and an example is presented by Figure-1.
Zig, then Zag
Sketching a road or walkway that zigzags is only slightly more involved than drawing a straight walkway.
You can, of course, just draw what you see in front of you without concern for the effects of perspective, as in Figure-2A. But there are times when the application of perspective principles can make your sidewalk more convincing, like in Figure-2B.
The road in Figure-2B is just an assemblage of three street segments, each like the road in Figure-1. Figure-3 shows each segment individually as it stretches toward its vanishing point.
When put together, the three sections become a zigzagging walkway as illustrated in Figure-4A. Notice that since each road section goes off in a different direction, each has its own vanishing point (labeled V.P.1, V.P.2, and V.P.3).
By smoothing the sharp corners, our zigzag walkway becomes a gently curving country road (Figure-4B).
The Wide and The Narrow
An important question to ask when drawing a zigzag path is: How wide should each section be? For the drawing to make sense and look convincing there needs to be a logical relationship in the widths of the various sections, such as is seen in Figure-5A. What is not wanted is a picture like Figure-5B, which appears random and ill conceived.
To keep the width of each section consistent with the widths of the other sections of the path, some sort of reliable system is needed. There is such a system and it is quite simple: draw a horizontal line across the road where it takes a turn and use the line to gauge what the width the new section should be at the turn. For clarity, the process is described as follows.
Draw the first section of road to its vanishing point (V.P.1 in Figure-6A).
Decide where the road will turn and draw a horizontal line across the road at that location (shown as dotted line a-b in Figure-6A), and then place the vanishing point (V.P.2) for the next section of roadway.
Connect V.P.2 to Point-a with a line, and to Point-b with another line (Figure-6B). Points-a and -b determine the width of the second section of road where it branches away from the first part.
Add subsequent sections of road in the same manner by drawing a horizontal line across the road where it takes a turn. Figure-6C illustrates a third segment, with Point-c and Point-d marking the width at the start of the new road section.
Up the Down Roadway
Not all streets sit on the ground. Some may be elevated, like a bridge, and others might be buried below ground, such as a cross-city expressway. Regardless which of these situations you may be confronted by, in all three scenarios the road is parallel to the ground and therefore all have a vanishing point on the horizon (see Figure-7A). If all of the streets head in the same direction (are parallel to one another), they all share the same vanishing point (Figure-7B).
All surfaces parallel to the ground recede to a vanishing point on the horizon. When horizontal surfaces are also parallel to one another, they all recede to the same vanishing point on the horizon.
Normally we don’t have to worry about where the vanishing point is for an individual path; it is sufficient just to let it dwindle in size into the distance. However, when confronted with something like a double-decker bridge (or a triple-decker as in Figure-7B), it is important that all the levels of the roadway appear to recede to the same vanishing point if the drawing is to be believable.
Over Hill and Dale
Thus far only paths that are parallel to the ground have been addressed, but some paths climb up hills and others dip into valleys.
In the case of an incline, a road shrinks upward or downward into the distance. If it is an ascending incline, its vanishing point is above the horizon line in the sky (Figure-8A), and a descending incline has its vanishing point below the horizon (Figure-8B).
When ascending, descending, and horizontal surfaces recede in the same direction, their vanishing points all fall on the same vertical.
A flat road, of course, has its vanishing point on the horizon. When a flat road has sections that ascend and descend, all three segments – flat, ascending, and descending – have vanishing points that fall on the same vertical. In other words, they are directly above and below one another as in Figure-8C.
The illustration below, Figure-9, incorporates all the ideas discussed in this section, such as inclines and multi-level roadways.