https://catalog.data.gov/dataset/viewsheds-from-key-observation-points-for-homestead-nm-of-america-national-monument-home
Department of the Interior - Viewsheds from Key Observation Points for Homestead NM of America...
Visibility viewsheds incorporate influences of distance from observer, object size and limits of human visual acuity to define the degree of visibility as a...
department of the interior
https://www.nps.gov/subjects/nightskies/2016workshop.htm
Workshops illumine importance of dark sky viewsheds - Night Skies (U.S. National Park Service)