BumpMap

Bump mapping is a computer graphics technique used to simulate bumps, wrinkles, and other surface irregularities on a 3D model without actually adding more geometry. It achieves this by manipulating how light interacts with the surface, creating the illusion of depth and detail.

A bump map is typically a grayscale image. The brightness values in the image are interpreted as height displacements. Darker areas represent lower points on the surface, while brighter areas represent higher points. When rendering the 3D model, the graphics engine uses this height information to perturb the surface normals, which are vectors that define the orientation of the surface for lighting calculations. By altering the surface normals, the way light reflects off the surface changes, making it appear as if the surface has physical bumps.

This method is significantly more efficient than adding real geometric detail, as it avoids the computational cost of rendering a vastly increased polygon count. It is widely used in video games, film, and other applications where realistic surface textures are desired without compromising performance. Bump mapping is a form of non-photorealistic rendering, as it manipulates lighting rather than geometry. While it doesn't change the actual shape of the model, it effectively fakes surface detail for visual purposes.