- Stick Close (the shape of an object vs. shape of its shadow)
- Stick 'em Up (the length of a shadow)
- A Stick In The Mud (the direction of a shadow)
- Sticks and Stones Make Shadows (plotting the shadow from a stick)
- Pick Up More Sticks (plotting the shadow from a box)
- Stick it to 'em (plotting the shadow of a house)
- Stick to Your Guns (conclusion)
THE SHADOW KNOWS
Drawing shadows is really rather straightforward, especially when drawing from observation. What might make it difficult is a lack of understanding about why a shadow looks the way it does.
A cast shadow is like a distorted clone of its parent object. It is not a generic shape.
In the figures that follow, we see the shadows cast by two pears. Figure-1A shows the shadows as ovals, and in Figure-1B they are simple horizontal bands.
If we took away the objects and left behind just the shadows (see Figures 1C and 1D), we would have no idea what kind of objects made the shadows. These shadows are simplistic and generic. They have little connection to the objects casting them.
A shadow should tell us something about the object making the shadow by echoing the shape of its parent object. Figure-1E fulfills this requirement with a shadow that has a specific shape that is related to the shape of the group of pears. In this case, if the objects were removed and only the shadow remained (Figure-1F), it is possible to figure out what kind of object (or, objects in this instance) produced the shadow.
Stick ‘em Up
Consistency and logic is one of the main concerns when rendering shadows. A drawing or painting in which shadows vary wildly in length defy belief (refer to Figure-2A).
Presumably, all objects in a scene are being affected by the same light source. If that is true, then all shadows will be similar in length (Figure-2B). For example, if the light source is the sun and it is almost directly overhead as in Figure-2C, cast shadows are short. When the sun is far away, shadows are longer (Figure-2D).
A shadow is longer when the light source is distant, and shorter when the light source is near.
Similarly, when the sun is high in the sky shadows will be short (Figure-2E), and when it is low near the horizon shadows tend to be long (Figure-2F).
A shadow is longer when the light source is lower, and shorter when the light source is higher.
A Stick in the Mud
All shadows in a scene should appear to emanate from the same light source or sources. There should never be a situation like that in Figure-3E, where there is no coherent structure.
Cast shadows radiate away from the light source.
In general, if the light is in front of the object (behind you), the shadow stretches away from you and into the distance (Figure-3A). The reverse is true when the light is behind the object; that is, directly ahead of you (Figure-3B). A light on the left throws the shadow rightward (Figure-3C), and casts it leftward when the light is to the right (Figure-3D).
Sticks and Stones Make Shadows
If we know the location of the light source, it is relatively easy to predict where a shadow will fall and how it will look. This ability is particularly useful when working from imagination, but also for helping to understand what we are seeing when working from direct observation.
Imagine a light bulb (L.S. in the diagrams) mounted on a pole that rises from the ground, and a stick standing up nearby.
Shadows emanate outward from the direction of the pole, and can be plotted by simply drawing a line from the pole’s base (labeled S.V.P.), through the bottom of the stick, and onward. This is Line-A in the illustrations.
We can then easily determine the length of a shadow by connecting the light source (L.S.) to the top of the stick with a line (Line-B), and then continuing Line-B until it crosses Line-A.
The point at which Line-A and Line-B intersect marks the end of the stick’s shadow.
Pick Up More Sticks
To predict the shadow cast by a solid object like a box, treat the box as an arrangement of sticks.
Shown in Figure-5A is a box with a nearby pole-lamp. Notice that the box is transparent so that we can see all four of its vertical edges, including the one in back that would be hidden from view if the box was an opaque solid.
Figure-5B shows four upright sticks, with each stick representing one of the four vertical edges of the box.
Following the procedure outlined previously in Figure-4, the shadow cast by one of the sticks has been plotted in Figure-5C (S1 for Shadow-1).
In Figure-5D, the shadows for the remaining three sticks have been diagrammed. For clarity, each stick and its shadow is a different color from the other sticks.
To complete the shape of the box’s shadow, just use the sticks and their shadows as a guide as was done in Figure-5E.
Figure-5F shows the finished rendering.
Stick it to ʹem
Calculating where the shadow of a more complex object would fall, such as a house, is no more difficult than the method used for a simple box. In this exercise, however, instead of a lamp as the light source, we will use the sun.
When a lamp is the light source, shadows radiate from the base of the lamp, which sits on the surface of the ground. We can imagine the sun being like a light bulb sitting atop a pole, except the base of this pole does not rest on the surface of the ground. Instead, it is anchored to the horizon line. Here we have a picture of a house beneath a sun that is mounted on a pole. As before, L.S. is the Light Source, and S.V.P. indicates the Shadow’s Vanishing Point. In the series of diagrams that follows, H.L. means Horizon Line.
The body of the house is essentially a box and its shadow has been constructed in the same way the shadow for any box would be. The box-like shape of the house has been reduced to four upright sticks, the shadow of each stick has been plotted, and then the shadow of the box as a whole was described using the stick-shadows for guidance.
Finding where the shadow from the peak of the roof falls is really quite simple. Just imagine the peak being supported by a tall stick. Plot the stick's shadow, and then connect the tip of the stick's shadow to the shadow of the house to describe the shape of the eaves' shadow.
The chimney is just another box. One must be able to visualize, however, where the base of that box sits in order to draw its shadow. That is the approach taken here.
Now, with all the elements in place, they can be combined to produce a cohesive image.
Stick to Your Guns
When drawing from observation, it is rarely necessary to mark light sources and vanishing points in order to plot out a cast shadow. After all, it is all right there in front of your eyes. Nonetheless, by understanding the logic and structure behind what you are seeing, you will be able to create more believable and accurate drawings based on reality.