A question better suited to the FIRST forums but here's the answer anyway.
The outer square is about 1" high. On top of that the circular region is, I believe 12" and the center triangle is about 20" off the square.
I'm supprised you would ask this, don't you have at least some parts of the field built?
If you need more measurements though, check out the following page on the FACE OFF! field,
http://www.usfirst.org/community/ftc/content.aspx?id=6654, here they have links to PDF schmatics of the field, don't try to measure the drawings with a ruler and apply a scale, they aren't to scale, just follow the printed dimensions.