Without these two elements, objects would appear flat. Highlights are a result of light illuminating or reflecting off an object. Shadows exist where the light cannot reach. Light and shadows differentiate parts of an object that are at different depths. Figure 4.28 demonstrates how light and shadows affect the perception of depth. Both images are the same. The image on the right has been flipped vertically.
Figure 4.28: Depth perception based on light and shadow.
Notice what happens to the highlights and shadows and how depth is perceived. The raised bumps in the left image become recessed pits in the right image. Surface shading defines form by giving an object a three-dimensional feel. In Figure 4.29 the light is coming from the left. The highlights showcase the light’s angle and define the blue ball’s smooth surface. The gradient shading across the ball’s surface shows the falloff of light around the object. It helps illustrate the object’s spherical shape. The illusion of roundness is achieved through the curvature of the shadows near the bottom. The cast shadow underneath the ball also helps establish where the light is coming from.
Figure 4.29: Light and shadows define the surface of the ball.
Having Some Depth
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