Part of being a great artist is to understand painting perspective. This will aid you in creating believable 3-D objects. Here are some tips for helping you understand the composition of realistic looking objects.
One rule is to prevent objects in a painting from “kissing” each other. Do not have two objects just touching each other as that will look awkward. Every object or subject in a painting should be standing definitely apart in the scene or deftly overlapped. If the objects are “kissing” the perspective in the painting will be thrown out of whack.
One way to keep a painting in perspective is to paint the background first. Then paint in any objects in the foreground. Another tip is to paint in the brightest color you have on your palette first and then create shadows and sculpting effects with darker colors later.
When painting in a realistic way light sources or light directions are also completely crucial to having it look believable. Some painters make a viewfinder which helps them find the right proportions to compose a painting.
Focus is also a component of making believable three dimensional objects in paintings. Cropping out the elements that you don’t want in your composition can trick the eye into making it more believable.
However perspective is absolutely crucial as it refers to our point of view and where lines converge. Lines that are all parallel to each other in a painterly scene are called the vanishing point. They will always converge or vanish in a drawing. The exception to this rule of realism is lines that lie parallel to the picture plane in 3D perspective.
Foreshortening of objects in the foreground is also a rule of perspective. Things that are further away are drawn smaller as they recede into the distance.
There are other rules as well. Objects which are lower than the viewer’s eyes will appear below the level of the horizon, and the viewer will be able to see at least a little bit of their tops. Objects which are entirely above eye level will appear above the horizon, and the viewer will be able to see at least a little bit of their undersides.
In perspective painting most shapes don’t look real unless they are slightly distorted unless they are parallel with the picture plane. Circles will appear as ellipses.
There are also one point, two point and three point perspectives in each drawing. It is best to take a drawing class or get a great book on the subject to understand these concepts fully.