Generating textures for games and virtual worlds is a time consuming task, to give you an example any big budget film or game may have well over 50% of the development budget assigned to creating 3d models and the images which cover them to make them realistic.
I’ve talked about procedural content generation before, but to give you an idea of it’s capabilities is a picture generated by the Graphic Designer Toolbox.
Looks pretty creepy, but the interesting thing is that it is created by a few blocks of mathematical algorithms rather than designed by hand. Simply swapping in different algorithms can create entirely different effects, from clouds, to cities, mountains, deserts, and many other instantly recognisable features. The effort required to generate a tool box of features may be large, but once you have the toolbox and can begin chaining effects, a single skilled designer can outperform a team very quickly. Modern films such as Avatar used this along with other PCG techniques to generate a whole alien worlds fauna and flora – without such methods it simply would not have been possible.