While there are many techniques available to create depth in a two dimensional image, the following six tips will help you easily create depth and volume in your digital images.
Overlap your Photoshop layers
or Illustrator objects. When one object covers part of a second object, the first seems to be closer to the viewer.
Objects should also "overlap" with the edges of the composition, or flow outside of composition. It is not important to fit the entire layer's color content in the workspace. Sometimes, it is most effective to let the layer extend beyond the document's edge.
Pay attention to Size. Large objects appear to be closer to the viewer than small objects, because the farther an object is from you, the smaller it appears.
Size Tip: Make the closest objects in a composition a larger size. The object does not need to radically larger to accomplish this illusion. For example if you are creating a still life of 5 oranges, the orange in the front can be slightly larger.
3. Placement ( Placement and Size work closely together)
Objects placed low on the picture plane seem to be closer to the viewer than objects placed near eye level. The most distant shapes are those the seem to be exactly at eye level.
Place the objects that you would like to appear closer in the bottom 1/3 of the composition.
Brightly colored objects seem closer to you and objects with dull light colors seem to be father away. This is called atmospheric perspective. The air around us is filled with smog, dust particles, mist or moisture and this creates a haze. Therefore, if a lot of air separates you from an object, the color of the object looks faded.
Objects with clear, sharp and visible details seem to be closer to you. Objects that lack detail and have hazy outlines seem father away.
Detail tip: Embellish the items that you would like to appear closer to you and make the items that you would like to appear further away with less detail.
6. Use Converging Lines
Linear perspective is one way of using lines to show distance and depth. As parallel lines move away from you they seem to move closer together two the horizon line. Consider looking down a long stretch of highway. It appears that the road becomes very small, but you know that this is not true. Use this illusion to your advantage!
Sometimes, lines appear to meet at a point on the horizon line called the vanishing point. Diagonal lines create more motion in a composition and guide your viewers eyes toward the horizon. The use of converging lines is a highly effective way to direct a viewer into you composition.