[PyMOL] Measuring surface roughness using Pymol

[Andy Cheesman]

Hi people

I've been using pymol to render molecule models which represent a 
surface and I was wondering if it possible to extract the Surface view 
information of a molecular to a python object like an array. I'm hoping 
to use this information to investigate the roughness along a particular 
crystallographic axis.
Any pointers would be greatly appreciated.
Thanks

Andy