Cognised existence: A building is a roofed, permanent physical structure that shelters human activity. It has use, age, size, and technical characteristics — and it occupies space, but its geometry may come from different sources than its attributes.
Question: What buildings exist at a location and what are their characteristics?
What is a Building?
A building combines two kinds of data: registry attributes (what it is, when it was built, how it’s used) and geometric footprint (its shape on the ground). These often come from different datasets. Understanding which to query depends on what you need.
Realisations
1. BygningerOgBoliger (BBR) — Attributes
BBR is the national building and housing register. It carries detailed attributes but no native geometry. Geometry arrives via joins.
Spatial Access Path
bygning (building with attributes)
│ FK: bygning → grund → jordstykke (via Matrikel)
│ OR: bygning → adresse → husnummer → adgangspunkt (via DAR)
▼
Two routes to geometry:
Route A: grund → jordstykke.geometri (parcel footprint — approximate)
Route B: husnummer → adgangspunkt.position (point — geocoded)
Route C: Join to GeoDanmark bygning via shared identifier (precise footprint)
Entity Hierarchy
| Entity | Role |
|---|---|
| bygning | The building: use code, construction year, area, floors, heating |
| enhed | Dwelling or commercial unit within a building |
| etage | Floor level |
| opgang | Staircase / entrance |
| grund | Ground parcel the building sits on |
| tekniskanlæg | Technical installations (heating plants, solar panels) |
Key Attributes
| Attribute | Description |
|---|---|
byg_anvendelse | Building use code (residential, commercial, industrial, public) |
byg_opfoerelsesaar | Year of construction |
byg_areal | Area in m² (footprint, gross, net variants) |
byg_antal_etager | Number of floors |
byg_varmeinstallation | Heating type (district heating, gas, electric) |
2. GeoDanmark — Geometry
GeoDanmark provides the authoritative building footprint polygons as part of the national topographic dataset. These are photogrammetrically measured outlines.
Spatial Access Path
GeoDanmark.bygning → polygon geometry (direct, no joins needed)
Join to BBR: Match GeoDanmark footprints to BBR buildings via shared spatial location or building identifier to combine attributes + geometry.
3. OpenStreetMap
OSM contains building footprints with basic attributes.
| OSM Tag | BBR Equivalent |
|---|---|
building=yes/residential/commercial/... | byg_anvendelse |
building:levels | byg_antal_etager |
start_date | byg_opfoerelsesaar |
Spatial access: Direct polygon geometry on the building way. Less detailed attributes than BBR but openly available.
Geometry Representations
A building query must declare which geometric encoding is used. These representations are not interchangeable.
| Rep ID | Source Dataset | Geometry Type | Native CRS | Field Path | Suitable For | Not Suitable For |
|---|---|---|---|---|---|---|
buildings_bbr_centroid | BBR (BBR_Bygning) | Point | EPSG:25832 | byg404Koordinat.wkt | Density mapping, point-in-polygon queries, proximity counts | Area statistics, footprint overlap, spatial join to polygon layers |
buildings_geodanmark_footprint | GeoDanmark | Polygon | EPSG:25832 | geometri | Area calculation, footprint overlap, visual representation, join to BBR attributes | Network routing |
buildings_dar_address_point | DAR (husnummer.adgangspunkt) | Point | EPSG:25832 | adgangspunkt.position | Geocoding, address-level mapping | Building-specific attributes (requires join back to BBR via husnummer) |
buildings_osm_footprint | OpenStreetMap | Polygon | WGS84 | way geometry | General mapping, open-data contexts | Official Danish register accuracy, bitemporal analysis |
Default assumption is wrong: BBR centroid is the easiest geometry to extract but is not suitable for area statistics, shadow/solar analysis, or any operation requiring the building outline. If the question involves shape, size, or spatial overlap — select buildings_geodanmark_footprint and join to BBR for attributes.
Classical Theme References
| Standard | Theme | Link |
|---|---|---|
| ISO 19115 | Structure | |Structure |
| INSPIRE | Buildings | |Buildings |
| UN-GGIM | Buildings and Settlements | |Buildings and Settlements |
Temporal Model
Bitemporal in BBR. GeoDanmark footprints are updated periodically (annual campaign). Historical building states via virkningFra/virkningTil in BBR.
Realised By Links
- Bygninger og boliger (collection)
- GeoDanmark (collection)
Unmatched Realisations
- OpenStreetMap
Realised By Links
- Bygninger og boliger (collection)
- GeoDanmark (collection)
Unmatched Realisations
- OpenStreetMap