for the lego fans amongst us

I am always amazed at these life size LEGO builds. Where do they start when an idea like this comes to mind. Is there some CAD computer program that converts drawings into LEGO parts lists? Hard for me to fathom that they just start building from scratch.

BTW: How the heck is that bike standing up?

Thats a great idea to have the real one side by side with this.

Initially, the only such program I remembered was LSculpt, but it strictly converts triangle meshes into (assembled) brick built LDraw or MPD files. It doesn't generate instructions, though. However, I've just found BrickR and Brickify (which do generate instructions, check for stability and use different file formats) as well.