Which type of camera mount requier for 3d mapping

I am using apm2.6 quadcopter frame. I wanted to creat a 3d map of my campus. So which type of camera mount requier,either front facing or downfacing?

Downfacing. Best results with the look straight down

Yes, straight down for 3D surface mapping then passing the images through suitable software to generate the 3D surface model.

You will want to work with 70% to 80% overlap of the images.