Take or Draw 3D Images
Here we learn to draw 3D imagery (or otherwise capture or create it) based on natural as well as more artistic styles stemming from imagination.
To make sense of this, first review our brief 3D tutorial. It describes several new aspects of this process of creating 3D form and depth.
Light and Dark
Levels of light and dark can be made "different with distance" to create apparent depth. (right)
In this case, we can see the image getting less dark as it gets farther away.
This example also emphasizes the effect of overlapping, which is another powerful depth cue in itself.
Light or dark only have meaning when compared to the other. How different they are between things in the scene translates into how much distance they are apart.
Lightness suggests we are receiving light rays from things actually there. We also have energy literally jumping at us. But when we see darkness, this suggests that not only are no light rays approaching us but there is less of anything in front of us to be reflecting light in the first place. So most of the time, making things darker with distance makes them less forceful. That suggests this to be the more effective way to draw 3D or take pictures. By doing the reverse, a dark object set against a white background can resemble a hole or dent in the picture. (left)
But since depth can be achieved with change across distance in almost any way, the use of dark against light can still be an effective way to draw 3D as shown in our first illustration. Neither light nor dark really have any more value over the other.
Artistic Depth Cues
Almost any apparent depth change ("difference with distance") you can achieve will create some kind of a depth cue when you "draw 3D."
The most depth cues normally found in books is somewhere around eight or ten. However, the actual number is certainly much more extensive than what is even contained in this draw 3D tutorial and can be considered limitless.
There are also ways of creating depth cues with the aim of providing depth in more creative and interesting ways. For example, one can just remove details with distance while drawing. (right) Objects may even be their same levels of light and dark here; they are simply made with less detail as they go farther away from us.
Such an artistic depth cue, as I call it, has no natural basis. Most or all details would normally remain present, they can just be more difficult to see when smaller. Details may also blend together to make an overall smoother look.
Other types of artistic depth cue could be created by using different pencil or brush strokes as things get farther out into the distance.
You could also draw 3D objects that are closer with thicker lines than farther ones. (left) This artistic depth cue doesn't exist in reality since objects are not surrounded by lines. Yet, this still works in accordance with standard depth cue behavior of having less of something with more distance.
Other ways of giving scenes less with distance to enhance depth include smaller, simpler or fewer paint strokes, creating softer textures, duller surfaces and so on. Just about anything you can do to make distant things look "less like" closer things should be effective in creating a 3D effect when you draw or paint.
Unlike most depth cues, artistic depth cues even can stress the specific distance of a subject, as with focus (see earlier tutorial), gradually reducing things as they depart from that one position, both closer and farther from it.