As a first motivating step, let's have a look at some part of the "result" of our example:
Quite impressing, isn't it? And as mentioned above, this is only a small part of the big thing that we are going to generate. Stay with us...
Of course, the most difficult part in generating pictures by using collage grammars are the collage grammars! So, the first real step has to be the definition of the underlying collage grammar.