Different appearances
 

I am trying to make a small environment that consists of flat ground and a hill. To make the hill I used triangles and planes however, although I used the same texture for both planes and triangles, the one on the planes appears to be much darker. I have no idea why this is happening. Any thoughts?

There are several things that could be causing this, but it is most likely either something going on with your materials or smoothing groups. I'd also turn off the "use indicies" settign in the OSG exporter if you're using it, since this can sometimes cause unexpected behavior as well.