In this recipe, we will create a realistic rock material that looks like the samples shown in the following screenshot, using an image map. We'll see a material made with procedurals in the this recipe.
Image maps are particularly useful for several reasons: they already have the necessary color information of a natural surface ready to be used; they can be easily edited in any image editor to obtain different kinds of information, for example, high levels for the bump maps; and they are processed faster than procedurals by the software (procedural textures must be calculated every time). Moreover, they can nowadays be found easily on the Web for free, in several sizes and resolutions.
For our recipe, we'll use the rockcolor_tileable_low.png
image map, which you can find in the textures
folder provided with this cookbook. This is just a low-resolution texture image provided for the sake...