I am trying to understand viewshed analysis in ArcGIS 10.1.
After you add fields such as RADIUS1, AZIMUTH1 to your observer vector attribute table, does it automatically calculate visible/non-visible areas within the specified radius and azimuth? Or do you have to use a different tool?
What I really need to find out is the areas visible from each monument location (including whether the monuments themselves are visible to each other, if they are close), in such a case what would be the best way to approach this?
Also, is it necessary to always convert xy coordinates of sites (already added as File Geodatabase Feature Class) to Observer points using observer points tool? I am only asking because for some areas, I have more than 16 monuments and I think you can only have a max of 16 observation points.
Best Answer
Set up your observer vector attribute table to contain the additional fields (RADIUS1, AZIMUTH1 etc). I haven't used viewshed in Arc for a while as I do it in other ways now but something at the back of my mind makes me think the field names might be case-sensitive (that might have been for the old ArcInfo 7.x on Unix though and might not apply to modern ArcGIS 10.x on Windows). In any event, I always used to name the fields exactly as per the documentation.
If you are testing the visibility of an object in the landscape from all locations (i.e. in this case your points represent a target and not the Observer), just be careful to get OFFSETA and OFFSETB round the right way! Other than that, it is very straightforward.