Rendering glass with realisticly non-flat appearance

Good post by The Revit Kid http://bit.ly/1eZHy1t - glass sheets in curtain wall are never truly flat and often distorted by differential exterior - interior pressure so that whats reflected in the real world is often slightly distorted. Hers his solution which involves changing the material used from glass to glass block (material > appearance cube and change to a bump map (research needed to find suitable) follow YouTube http://bit.ly/1eZLgb8