I am a graduate student of micorbiology. My problem is to find out the average intensity of a particular UVC light fixed on a ceiling to an x area. For that I need to calculate the view factor first. The shape of the absorbing area is a differential planar element and the emitting area is a finite cylinder. Here the problem is how much is average intensity required for a particular area (ex.10sq feet). Could you please explain me how to calculate the radiation view factor of an ultra violet light?