Urban Signal Grid (ESGI cells) — Ontology Crosswalk

Schema: pending (AXC-10 — schemas/urban-signal-grid/v1.0.md) Target standards: OSCRE IDM 2.0 (real-estate semantics), OGC API — Features (OGC 17-069r4), DCAT-US v3.0 Authority: OSCRE International, Open Geospatial Consortium, U.S. Department of Commerce Status: FAIR-aligned, OGC API — Features compatible Dataset SPDX license: proprietary (all tiers — this is the Codex commercial flagship)

1. Why OSCRE IDM + OGC

The Urban Signal Grid is the single dataset where institutional real estate firms expect semantic alignment with OSCRE's Industry Data Model (IDM). OSCRE IDM 2.0 defines the canonical "property-level signal" object model used by CBRE, JLL, Cushman & Wakefield, Blackstone, and most institutional REITs. OGC API — Features makes the grid programmatically queryable as a standard spatial feature collection; every enterprise GIS pipeline consumes that API shape.

2. Dataset-level (DCAT-US v3.0)

DCAT-US field	Value
`dct:identifier`	`urn:axiom:codex:dataset:urban-signal-grid:v1.0.0`
`dct:title`	"Axiom Urban Signal Grid (ESGI)"
`dct:description`	"454K H3 resolution-8 cells across 22 U.S. metros, each scored across 8 signal groups (business vitality, population momentum, demographics, economic strength, development pipeline, accessibility, safety/environment, amenity demand)."
`dcat:keyword`	`["real-estate", "urban", "h3", "site-selection", "signals", "esgi"]`
`dcat:theme`	`["http://publications.europa.eu/resource/authority/data-theme/ECON", "...REGI"]`
`dct:accessRights`	RESTRICTED (commercial+)
`dct:license`	Codex Commercial License

3. Cell-level crosswalk → OSCRE IDM 2.0

OSCRE IDM's relevant object: PropertySignalSet. Each H3 cell is mapped to one or more PropertySignalSet instances (aggregating to whatever parcel resolution the buyer needs).

Codex field	OSCRE IDM
`h3_index`	Codex extension (H3 is not in OSCRE vocab; emitted as an alternative spatial identifier alongside the centroid)
`metro_slug`	`PropertySignalSet.market.marketIdentifier`
`composite_score`	`PropertySignalSet.aggregateScore`
`score_low` / `score_high`	`PropertySignalSet.confidenceInterval.{lowerBound, upperBound}`
`confidence`	`PropertySignalSet.confidence`
`business_vitality`	`PropertySignalSet.signalGroup[id="business_vitality"].value`
`population_momentum`	`PropertySignalSet.signalGroup[id="population_momentum"].value`
`demographics`	`PropertySignalSet.signalGroup[id="demographics"].value`
`economic_strength`	`PropertySignalSet.signalGroup[id="economic_strength"].value`
`development_pipeline`	`PropertySignalSet.signalGroup[id="development_pipeline"].value`
`accessibility`	`PropertySignalSet.signalGroup[id="accessibility"].value`
`safety_environment`	`PropertySignalSet.signalGroup[id="safety_environment"].value`
`amenity_demand`	`PropertySignalSet.signalGroup[id="amenity_demand"].value`
`scored_at`	`PropertySignalSet.scoredAt`
`scoring_version`	`PropertySignalSet.methodology.version`

OSCRE IDM allows custom signal groups via signalGroup[id="..."] extensions; the eight Axiom signals are published under a documented axiom: namespace.

4. Spatial crosswalk → OGC API — Features

Each H3 cell becomes an OGC Feature:

{
  "type": "FeatureCollection",
  "links": [
    {"rel": "self", "href": "https://codex.axiomlayer.io/api/features/urban-signal-grid"}
  ],
  "features": [
    {
      "type": "Feature",
      "id": "88283082b9fffff",
      "geometry": {
        "type": "Polygon",
        "coordinates": [/* H3 cell boundary */]
      },
      "properties": {
        "h3_index": "88283082b9fffff",
        "metro_slug": "san-francisco-ca",
        "composite_score": 0.78,
        "confidence": 0.91,
        "scored_at": "2026-04-01T00:00:00Z",
        "axiom:signals": {
          "business_vitality": 0.82,
          "population_momentum": 0.71,
          "demographics": 0.64,
          "economic_strength": 0.79,
          "development_pipeline": 0.88,
          "accessibility": 0.73,
          "safety_environment": 0.69,
          "amenity_demand": 0.81
        }
      }
    }
  ]
}

Codex exposes:

Collection endpoint: GET /api/collections/urban-signal-grid
Feature endpoint: GET /api/collections/urban-signal-grid/items/{h3_index}
Spatial filter: ?bbox=<minLon,minLat,maxLon,maxLat>
Attribute filter: ?composite_score=gte:0.7

5. Codex extensions

Under axiom: namespace:

axiom:h3Index
axiom:signals (object with 8 signal-group values)
axiom:pioneer_flag (boolean, promoted from POI dataset when present)
axiom:tier (scoring tier: low / mid / high)

6. FAIR compliance

Principle	Status
F	✅ — DCAT-US + OGC `/conformance` + `/collections` discovery
A	✅ — HTTPS API with OpenAPI 3.1 description
I	✅ — OSCRE IDM 2.0 + OGC API Features + JSON-LD
R	✅ — Versioned, documented methodology (AXC-10 spec)

OGC API — Features conformance classes: Core, HTML, JSON, GeoJSON, OpenAPI 3.0. OSCRE IDM: Level 2 (property-signal extension).

7. Deviations

No per-parcel resolution. The grid is inherently cell-based (H3 res 8 ≈ 0.74 km²); OSCRE IDM accommodates sub-parcel-level signals but our product is explicitly cell-grained.
OSCRE IDM in XML. OSCRE publishes canonical XSDs; Codex distributes JSON-LD with OSCRE IRIs aligned by term. An XML-shape sidecar will ship as a v1.1 option if institutional buyers require it.

8. Changelog

v1.0 (2026-04-16) — Initial crosswalk. AXC-10 schema spec pending.