When we look around us in the real world we already have a built-in spatial understanding, we “know” that our world or the objects in our room exist spatially. Some things are close to us and other things are further away. We could not navigate through our daily lives if we did not have this spatial awareness.
The Appearance of Depth in Traditional Painting
In traditional painting there are ways of creating the appearance of depth on a canvas (or iPad screen). Probably the most useful way of creating depth in Still Life painting is to use overlap. When you are setting up a still life group, if one object overlaps another it hides part of the object behind. The brain reads this as depth. So the way you set up a simple Still Life group really matters.
Look at the Vermeer painting. The basket of bread overlaps the container which overlaps the standing figure which is front of the wall. Like Vermeer you draw or paint from one view-point only, so make sure you set up a good simple still life group to work on and overlap is working for you. This is how you start the 3D illusion on your 2D surface!
Light and shade
Artists can emphasise volume or distance with the use of light. Objects near a source of light can appear brightly lit on one side and recede into shade as they turn away from the light. (see Chardin’s Painting below.) Also objects near the front of a canvas can have strong contrasts and objects further away are more muted. Mountains in the distance can be pale and misty while trees or objects in the foreground strong and dark.(see Turner’s painting below).