After producing the heightmap in Photoshop well need to import it into Bryce for further manipulation. Remember that we started our heightmap as a 512x512 canvas. This holds to Bryces rule of 2 precept so that the cityscape will appear parametrically proportional around its periphery (try saying that 3 times aloud really fast while Peter packs his pickle) when brought in but what we now need to do is adjust the overall height and this is dictated by individual preference guided by artful aesthetics. This might be just the first quadrant of a larger cityscape stage that you have envisioned in your mind so height becomes important to the overall scale of the final assemblage.