1) The first method is aerial perspective. When artists use aerial perspective they represent objects or people in the distance smaller or fainter, and add a more blue hue to them. You brain automatically treats the added blueness as shadows, thus creating a back-ground.
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2) The second method is linear perspective. Artists use linear perspective when the shape, size, and position of the drawn objects are determined by using lines that converge or meet at a single point on the canvas' horizon. When you use linear perspective you can add to or create a back-ground but artists most commonly use linear perspective when creating a middle-ground.
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3) The third method is basic perspective. When artists use perspective you can create a tunnel, or a deep water well on a flat canvas. Perspective creates a visual illusion of three-dimensional objects, places, and people on two-dimensional areas. To create realistic perspective, artists use three layers. The fore-ground, the middle-ground, and the back-ground.
