Instead of randomly generating an entire, playable map, Firaxis's designers only use the CPU to generate a "height map" that contains simple coordinates and 8-bit height values.

ENGADGET: Primed: The crazy science of GPU compute Mobile

So, this approach requires one more layer of effort: converting the height map (or at least its visible tiles) into a "normal map" which is smooth and natural enough to be subjected to lighting effects and then displayed on screen.

ENGADGET: Primed: The crazy science of GPU compute Mobile

The first filter that is applied to the height map is a simple Gaussian blur, which the GPU handles with ease, but which -- if left to its own devices -- would simply smooth out all the dramatic extremes in the height map and leave us with a bunch of bland rolling hills.

ENGADGET: Primed: The crazy science of GPU compute Mobile