Data and accuracy
Every Sundrift answer carries a label naming what was modelled. This page is the long version of that label.
Accuracy tiers
| Factor | Preview today | Planned |
|---|---|---|
| Terrain | Global elevation model, ~20–40 m grid, with Earth curvature and standard refraction (k = 0.13) | Norway: Kartverket DTM 10 m as the premium tier |
| Buildings | Norway: OSM footprints as near-field silhouettes (within 800 m). Heights: measured where tagged, levels × 3 m, else a default 8 m — the mix is disclosed on every result | Global footprints (Overture); better height sources |
| Vegetation | Not modelled | Modelled forest stands with seasonal foliage — conifer opaque all year, deciduous transparent in winter. Stand-level models, never individual trees |
What the times mean
- "Direct sun" means the sun's position clears the measured terrain horizon. Thin cloud, haze and local obstacles are not modelled.
- Times are for the centre of the solar disc; first light from the upper rim arrives a minute or two earlier.
- Times use your device's clock and timezone.
- If elevation data is missing at a point, Sundrift declines to answer rather than assume flat ground.
Sources and attribution
- Base map: © Kartverket, used online per Kartverket's open service terms (CC BY 4.0).
- Elevation: Terrain Tiles on AWS Open Data (Mapzen terrarium format), compiled from open sources including USGS, ETOPO1, EU-DEM and others named in the registry.
- Search: Kartverket adresse and stedsnavn APIs (Norway); Photon (© OpenStreetMap contributors) worldwide.
- World base map: OpenFreeMap, data © OpenStreetMap contributors. Used automatically where Kartverket has no coverage.
- Buildings: © OpenStreetMap contributors (ODbL) — footprints and height tags from the Norway extract by Geofabrik.
- Solar geometry: SunCalc (BSD-2-Clause), run on your device.
- Map rendering: MapLibre GL JS (BSD-3-Clause).
Development preview: terrain worldwide (~20–40 m) and
building silhouettes in Norway. The premium terrain (Kartverket 10 m),
seasonal forest stands and the paid year report are in active development.
Nothing on this page is a promise of a date.