Bump mapping is a computer graphics technique used to add more realism to images without adding a lot of geometry.

Unlike texture mapping which adds realism by mapping images to geometric surfaces, Bump mapping adds per-pixel surface relief shading. This uses lighting properties and indicates which parts are dark and which are light on a texture. Bump mapping does this by changing the brightness of the pixels on the surface in response to a height-map that is specified for each surface.

A bump map is an array of values that represent an object’s height variations on a small scale. It is generally applied to surfaces that have a patterned roughness, for examples, strawberries, oranges, stucco, wood, water, etc.

The interaction of light with 3D model determines brightness and color when rendering a 3D scene. The geometric surface normal as a vector at each pixel position on the visible object is determined using trigonometry. The geometric surface normal then defines how strongly the object interacts with light coming from a given direction using Phong shading or a similar lighting algorithm. Light traveling perpendicular to a surface interacts more strongly than light that is more parallel to the surface. After the initial geometry calculations, a colored texture is often applied to the model to make the object appear more realistic.

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