I am trying to create skyline based on 7 points within a neighborhood. The points are in a point shapefile without elevations (I am not sure if this file should be called 3D points). I also have a building footprint shapefile with building heights. When I run skyline (in ArcMap), I used the point file as 'Input Observer Point features', leave 'Input Surface (optional)' empty, and used the building footprint file as 'Input Features (optional)'. But when I run it, I got full circles around all points. This to me means that the points are not related to the buildings. I tried to add elevations into the point data, but it did not work. Could anyone give me suggestion on what I did wrong and how to fix it?