I am performing a Viewshed analysis in ArcGIS (10.1), and I use an OFFSETA (observer) of 1.7m and an OFFSETB (target) of 6m. The latter is the height of a typical building for which I wish to estimate the visibility across the landscape of a given study area. I would like to know: if a location (actually, a pixel) in the resulting binary Viewshed Raster is flagged as visible, I assume that a 6m-tall building placed at that location would be visible. But I also understand that we would not know if it is the whole building that would be entirely visible, or just (say) its top 1 meters.
In the context of a Viewshed analysis, is there a way to assess the amount of the building that would be actually visible?