i don't know if that makes sense but it could be interesting to split the views of any point into multiple segments, and then for each segment find the largest distance. next between two of these largest views find the shortest view. if the ends of each view are connected by lines the result would be a zigzag circle around the starting point that gives you a rough idea of the visible area.

most points would be on a slope so they would just have a half circle, only peaks themselves would have an all around view.