Smart Decimator?

Is there a smart mesh decimator that will decimate the flat or planar parts of the mesh and leave the rest alone? I have a very large mountain mesh and I want to reduce the poly count only on areas where the surface is flat and it would be nice if there was a tolerance adjustment. Anyone know of a way to automatically do this?

Decimator does do this, to a certain degree. It tried to keep polygons around sharp angles and remove those which are ‘flat’.

But if the Blender decimator doesn’t seems to be good enough for you, there is a pyredux script, which might give you more control.
http://blenderartists.org/forum/showthread.php?t=51609

It looks like pyredux is no longer available. I haven’t had any luck witht he polyreducer script either. I will try the decimate script again.