This section maps three widely-used geospatial metadata classification systems into the SPHERE tree. Each classical theme gets a page with its original definition, its location in the SPHERE hierarchy, and harvesting hints for discovering relevant datasets in metadata catalogs.
Why This Mapping Exists
Classical metadata standards (ISO 19115, INSPIRE, UN-GGIM) use flat lists of topic categories. This works for basic catalog search but breaks down when:
- A theme spans multiple domains (e.g., “Environment” monitors all physical spheres)
- Themes mix abstraction levels (orthophoto imagery at the same level as land use classification)
- There is no hierarchy to navigate — you must know the keyword to find the data
The SPHERE tree provides the missing hierarchy. Each classical theme maps to a sphere (branch), a subsphere (twig), and optionally threads (cross-domain connections). An agent harvesting a metadata catalog can use this mapping to route datasets into the right part of the tree.
The Three Classification Systems
| Standard | Themes | Purpose | Scope |
|---|---|---|---|
| |ISO 19115 Topic Categories | 19 | General-purpose metadata keywords for any geospatial dataset | Global |
| |INSPIRE Themes | 34 | Legally mandated data themes for European SDI interoperability | EU / EEA |
| |UN-GGIM Fundamental Themes | 14 | Core geospatial data themes identified by the UN for national SDIs | Global |
Cross-Standard Concordance
Many themes appear in multiple standards. Notable equivalences:
| Concept | ISO 19115 | INSPIRE | UN-GGIM |
|---|---|---|---|
| Addresses | Location | Addresses | Addresses |
| Elevation | Elevation | Elevation | Elevation and Depth |
| Buildings | Structure | Buildings | Buildings and Settlements |
| Transport | Transportation | Transport Networks | Transport Networks |
| Land Cover/Use | Imagery/BaseMaps/EarthCover | Land Cover and Use | Land Cover and Land Use |
| Population | Society | Population Distribution | Population Distribution |
| Geology | GeoscientificInformation | Geology | Geology and Soils |
| Orthoimagery | Imagery/BaseMaps/EarthCover | Orthoimagery | Orthoimagery |
| Water | InlandWaters + Oceans | Hydrography + Sea Regions | Water |
| Soil | GeoscientificInformation | Soil | Geology and Soils |
Key Threads (Themes That Cross Spheres)
These themes are inherently cross-domain — they are the “wind through the branches” of the SPHERE tree:
- Land Cover and Land Use (all 3 standards) → Socio-Technical Perception & Thematics primary, thread to Toposphere Imagery & Evidence
- Natural Risk Zones (INSPIRE) → Physical hazards (Lithosphere/Hydrosphere) + human vulnerability (Socio-Technical)
- Environment / Environmental Monitoring (ISO + INSPIRE) → Monitoring infrastructure (Socio-Technical) observing across all physical spheres
- Planning/Cadastre / Area Management (ISO + INSPIRE) → Human governance intent wrapped around physical space
- Farming / Agriculture (ISO + INSPIRE) → Resource utilisation (Socio-Technical) + Biosphere organisms
- Geology and Soils (UN-GGIM) → Lithosphere ↔ Pedosphere bridge
- Energy Resources (INSPIRE) → Lithosphere resources + Socio-Technical infrastructure
See SPHERE for the full protocol definition. See Leaves for purpose-specific dataset entry points.