In art, there are a number of ways to use perspective to obtain the illusion of depth, including using colors and graduated values of black and white, and accurately drawing the subject by applying the rules of the geometric system of perspective. In order to achieve perspective, you must make a number of observations. The forms or objects that you draw on a flat surface actually have depth and dimension in real life. As you view them and place their shapes and forms on a drawing surface, try to represent that depth to make the objects appear realistic and threedimensional. Objects appear differently when viewed from various positions. Because of this, it's important to establish the viewpoint, and stick with it. When observing a subject, you see depth and three dimensions. When you draw this subject onto a flat surface as it appears to the eye, you are drawing in perspective.