The service provides a scaled view of the horizon and terrain from a specified location, defined as a map point on Google Maps. It calculates a 'viewshed' from the location based on local terrain contours and depicts a view from the location highlighting mountains in the distance. It is intended to answer questions like, "Hey, what's that?" when viewing a horizon.
API methods support submission of a location, either as a panorama query or as a latitude/longitude. Methods adjust for day and time, and for atmospheric refraction, which changes the view of distant terrain due to bending of light through air.