# Lyon Multi-Epoch 3D Building Dataset

Cross-time entity matching benchmark using Lyon 3D city models (2009-2018).

## Data

| Epoch | Buildings | Format | CRS | LOD |
|---|---|---|---|---|
| 2009 | 2,348 | CityGML 1.0 | EPSG:3946 | LOD2 MultiSurface |
| 2012 | 2,281 | CityGML 1.0 | EPSG:3946 | LOD2 MultiSurface |
| 2015 | 7,693 | CityGML 2.0 | EPSG:3946 | LOD2 Solid |

Coverage: Lyon 1er, 2ème, 4ème, 6ème arrondissements

## Cross-Time Labels

| Pair | Total Matches | High Confidence |
|---|---|---|
| 2009 → 2012 | 2,209 | 2,168 (98.1%) |
| 2009 → 2015 | 1,236 | 448 (36.2%) |
| 2012 → 2015 | 1,238 | 461 (37.2%) |

Labels constructed using spatial proximity (centroid < 10m) + geometric consistency.
Confidence tiers:
- High: distance < 3m AND 0.5 < area_ratio < 2.0
- Medium: distance < 7m AND 0.3 < area_ratio < 3.0
- Low: distance < 10m