I have a group of observer points that I need horizon angles for (just East 0 deg and West 180 deg). I am thinking that I should be able to somehow extract these from the Viewshed, however the process is unclear. Does anyone know how this could be accomplished in viewshed or another application?
It is possible but the process is not exactly simple.
The first step is to use
Skyline tool to obtain skyline vertices (basically horizons). Then you need to convert vertices of skyline to points - tool
Feature Vertices To Points. Based on observation point and points from skyline you can calculate distance and horizontal angle using
Generate Near Table. From the result you can select your horizons - with angles 90 (East) a 270 (West) degrees (0 is North). With the knowledge of distance, Z value of skyline points and Z value + offset of the observer you can calculate the horizon angles.