Horizonsfrom

Horizonsfrom is a term used in geospatial analysis to describe the process of computing the horizon profile visible from a specific observation point on a digital terrain model. It captures how the landscape extends toward the horizon across different directions, highlighting the angles and distances at which terrain obstructs or reveals the view.

The phrase is not an established standard in major reference works, but it appears in informal discussions and niche GIS workflows as a way to emphasize the directional nature of horizon visibility. It is closely related to viewshed analysis, with horizonsfrom focusing on the angular envelope of the visible horizon rather than a simple binary visibility map.

Methodologies associated with horizonsfrom typically require a digital elevation model, an observer height, and a set of azimuth directions. For each direction, the approach traces terrain elevations away from the observer and determines the maximum obstruction angle along that ray. The horizon in that direction is defined by the line of sight that just touches the terrain. The result can be expressed as a horizon curve, a set of horizon angles, or a summarized profile across all directions.

Applications of horizonsfrom span urban planning, landscape architecture, solar access studies, and wind or telecommunication site assessments. By characterizing how far the visible horizon extends and at what angles, planners can evaluate visual impact, optimize viewpoints, or assess potential shading and line-of-sight constraints.

Implementation varies across software ecosystems. Horizonsfrom may be realized as a scripting workflow within GIS platforms or as a small, modular library that integrates with existing line-of-sight and viewshed tools. Its lack of formal standard means users may encounter differences in input formats and output representations.