Sorry guys for this question....just started c5p.  Played with it a little bit ..just to get to know all the tools , etc...and did a few step by step tutorials ,etc...
I'm going to work on a very simple, sci-fi looking building. Simple shapes ...should be easy to create it.
Ho do you set up the size for the building (or any real life object....like a car or a street scene or 
a bridge , etc..) ?  When you create a street scene which covers 4-5 city blocks...how do you start...size etc.. ?
Thank you very much