Calculate 360-degree horizon elevation angles from GeoTIFF elevation data.

Requirements

• Node.js 22+
• GDAL (brew install gdal / apt install gdal-bin)

Install

npm install @bridgerb/horizon gdal-async

Usage

import { loadElevationData } from "@bridgerb/horizon";

const elevation = await loadElevationData("path/to/elevation.tif");

const horizon = elevation.calculateHorizon(40.311259, -111.659330);
// Returns 360 results, one per degree

const partial = elevation.calculateHorizon(40.311259, -111.659330, 45, 135);
// Only directions 45° to 135°

API

loadElevationData(tifPath: string): Promise<ElevationData>

Loads a GeoTIFF elevation file. Call once, then query many times.

ElevationData.calculateHorizon(lat, lng, start?, end?): HorizonResult[]

• lat - Latitude in degrees
• lng - Longitude in degrees
• start - Start direction (default: 0)
• end - End direction (default: 359)

HorizonResult

• direction - Compass direction in degrees (0 = North)
• elevationAngleDegrees - Angle to horizon
• distance_km - Distance to horizon point

License

Unlicense - Public Domain