Angles of Observation / officer.com, 28 May 2008
http://www.officer.com/web/online/Technology/Angles-of-Observation/20$41565
"Keeping in mind thermal imagers cannot see through objects, we should change our angle of observation so that we are able to get a clear picture on our TI. During many surveillance observations, our viewpoint may be obscured or blocked by objects such as trees, debris, or other materials. By changing the position of the TI or ourselves, we can greatly improve our chances of seeing an image on our TI screen."