To show objects which don't have a uniform surface colour, the surface can be given a texture. This method, known as "mapping", places abstract, graphical patterns or photos on the model. Simulation programs provide extensive material collections in libraries to enable designers to show textures such as wood or exposed concrete. Using special mapping methods (bump mapping), microstructures can be modified so as to give the impression of three-dimensional surfaces.
A highly realistic impression results if by photos are assigned as textures to polygons. To ensure acceptable quality, the photo should be high resolution, be taken head-on and contain no light or other reflections. It must also be without distortions due to the lens.