# Geo

Geographic sources, manifests, and the tools that turn them into Blender and Unreal content.

OSM is layout data only. It is not authoritative for façade detail, height, or pavement, and it is never sampled as a texture or panorama source.

## Layout

| Path | Contents |
| --- | --- |
| `Geo/raw/` | Verbatim source responses and downloads, checksummed. Never edited by hand. |
| `Geo/manifests/` | One manifest per source: extract, DEM, and the local origin |
| `Geo/verification/` | Per-pass notes: address, footprints, bounds, street profile, cross-sections, elevation |
| `Geo/tools/` | Every geographic tool (Python, standard library only unless noted) |

Tools that build 3D content from these sources live next to their output in `Art/blender/*/` (`terrain_from_dem.py`, `street_mesh.py`, `site_assembly.py`, `blosm_blockout.py`) because they need Blender; their shared geo helpers and the unit conversion come from `Geo/tools/osm_common.py`.

## Tools

| Tool | Purpose |
| --- | --- |
| `osm_common.py` | Shared helpers: parse `.osm`, stitch and clip a street, project to UTM through PROJ, **and the single metres→centimetres conversion** (`to_unreal_local`) |
| `block_report.py` | Streets, boundary intersections, and the building set for a block, split by side |
| `block_height_report.py` | Every block building with its height **source** — tag, levels × 3.2 m, or a placeholder guess |
| `street_profile.py` | Carriageway width from crossings, sidewalk offsets, per-building setbacks |
| `street_section.py` | Cross-sections from the DEM: crown, gutters, kerb detection |
| `elevation_probe.py` | Samples 3DEP for relief and records the baseline for the release checks |
| `dem_stats.py` | Stdlib reader for the tiled GeoTIFF the 3DEP service returns; GDAL does not run on this host |
| `asset_metadata.py` | Writes and audits `<asset>.geo.json` sidecars: position, provenance, conversion |
| `mapbox_buildings.py` | Cross-checks every building's height against Mapbox `mapbox-streets-v8` building data (Tilequery per centroid), merging our OSM height + source with theirs and flagging matches, close, disagreements, non-building volumes. Needs `MAPBOX_ACCESS_TOKEN` in `.env`; caches responses under `Geo/raw/mapbox-cache/`, and **both the cache and its report are gitignored** (Mapbox terms restrict redistribution) |

## Unit boundary

There is exactly one conversion in the repository:

```
WGS84 (lat, lon) → EPSG:26911 (E, N metres) → project-local metres → Unreal centimetres
```

`Geo/tools/osm_common.py::to_unreal_local` is the only place that multiplies by 100. Per-asset sidecars record the result, and `asset_metadata.py audit` checks each saved sidecar against that function, so a file that drifts is caught rather than trusted.

## Current state

The extract, both El Capitan footprints, the demo bounds, the building sets, the street profile, cross-sections, and the 3DEP DEM window are recorded in `Geo/verification/` and `Geo/manifests/`. The local CRS and origin are fixed in `manifests/local-origin.md`.

Open items live in `TODO.md` under **Geographic data**.