A bump map creates fake detail on a mesh. They create the illusion of depth on a surface using light. Bump maps are usually grescale images that are limited to 8 bits of colour information – which is 256 different colours of black, grey or white. The values in in a bump map tell the software either up or down; whe the values get higher (or brighter) they are working their way to the white side of the colour bar; when they get lower, they’re working their way towards black. If the value hovers around the 50% mark then the result is grey.
Bump maps are easy to create in programs like Photoshop and are easily and greatly used for creating tiny details on models. They do however, break very easily if viewed from the wrong angle.
Normal mapping is a technique in 3D art that is used to fake lighting of bumps and dents on an object – its also a newer version of bump mapping. Its also used to make polygon models look more like high polygon models, it can add various details that can’t be modelled on low poly models and can be used to make harder edges and corners look more smooth. Normal mapping uses RGB information that directy corresponds to the X, Y & Z axis in 3D space. This RGB information tells the 3D program the exact direction of the surface normals are oriented in for each polygon.
Referred often to as normals, these also tell the 3D program how the polygon should be shaded.
2D texture maps are also added to a 3D model to provide a higher level of detail, wrapping around whatever 3D art you have or to modify certain attributes like colour, transparency, shininess, reflection, and higher detail.
These kind of maps physically displace the mesh to which they are applied but for detail to be created based on a displacement map, the mesh must usually be subdivided or tessellated so real geometry is created. Displacement maps can either be baked from a high resolution model or painted by hand and consist of greyscale values.