Cognised existence: Orthoimagery is a geometrically corrected aerial or satellite photograph — the surface as seen from above, with positional accuracy. It is the most intuitive spatial data: it shows what the world looks like.
Question: What does the Earth’s surface look like at a location?
Realisations
1. GeoDanmark Orthophotos
National aerial photography cooperatively produced by SDFI and municipalities.
Spatial Access Path
Raster tiles — no entity joins. Access by spatial extent.
Forårsfoto: leaf-off (spring), 12.5 cm resolution, annual
Sommerfoto: leaf-on (summer), 12.5 cm resolution, annual
2. Dataforsyningen Services
SDFI distributes orthophotos and historical imagery as web services:
- WMTS/WMS: Tiled map services for web applications
- Download: GeoTIFF tiles
- Historical archive: Aerial photos from 1944–present (variable resolution)
3. Copernicus (Sentinel-2)
Free European satellite imagery:
- 10m resolution, 13 spectral bands
- 5-day revisit time
- Global coverage
Spatial access: All realisations are raster — accessed by spatial extent query, no entity joins.
Cross-Domain Relevance (Threads)
- Toposphere Imagery & Evidence: Imagery is direct visual evidence of surface state at acquisition time.
- Socio-Technical Perception & Thematics: Thematic classifications derived from imagery belong to human interpretive partitioning layers.
Classical Theme References
| Standard | Theme | Link |
|---|---|---|
| ISO 19115 | Imagery/BaseMaps/EarthCover | EarthCover |
| INSPIRE | Orthoimagery | |Orthoimagery |
| UN-GGIM | Orthoimagery | |Orthoimagery |
Realised By Links
- GeoDanmark (collection)
Unmatched Realisations
- Dataforsyningen
- Copernicus