Beyond the techniques mentioned in this chapter, there are also many techniques based on drawing and painting using shadows and lighting to achieve 3D effects. This is a very useful way to add depth to a scene using, for example, a background that uses light and shadows to produce an illusion of there being much more to the scene than what's visible in the front.
It can also be used to add depth and details to an object's or character's textures. Also, it can mean the difference between flat-looking, lifeless worlds and characters, and both of them coming to life. This, however, is a topic far beyond the scope of this chapter. Nonetheless, there are many resources on the subject that can be found both online and elsewhere.