## GeoData Heightmap Export

This repository converts DGM1 elevation tiles into Unity-ready 16-bit PNG heightmaps and a placement manifest. It relies on GDAL for mosaicking, resampling, and scaling to UInt16 ranges Unity expects.

### Prerequisites
- GDAL installed with Python bindings (`osgeo` importable).
- Python 3.9+ available on PATH.
- DGM1 source tiles placed in `raw_dgm1/` as `dgm1_<utm_zone>_<easting>_<northing>.tif` (with matching `.tfw` files).
- Raw inputs (`raw_dop/`, `raw_3dgeb_lod1/`, `raw_3dgeb_lod2/`) are **kept out of git**; keep them locally or document how to fetch/regenerate.

### Repository Layout
- `raw_dgm1/` — input rasters (not versioned).
- `raw_dop/` — raw orthophoto downloads (JP2/J2W/XML), ignored in git.
- `raw_3dgeb_lod1/`, `raw_3dgeb_lod2/` — CityGML building tiles, ignored in git.
- `work/` — intermediates such as `dgm.vrt` and `_tmp.tif` files; safe to delete/regenerate.
- `export_unity/height_png16/` — final 16-bit PNG heightmaps for Unity import.
- `export_unity/tile_index.csv` — manifest mapping tile IDs to world bounds and global min/max used for scaling.
- `export_unity/ortho_jpg/` — cropped orthophoto tiles aligned to the terrain grid (JPEG + worldfiles).
- `export_heightmaps.py` — main export script.
- `export_ortho_tiles.py` — exports orthophoto tiles from DOP JP2 inputs using the terrain manifest.
- `AGENTS.md` — contributor guide.

### Quick Start
1. Export Unity heightmaps and manifest (builds `work/dgm.vrt` automatically if missing):
   ```bash
   python3 export_heightmaps.py
   ```
3. Import the PNGs into Unity Terrains using `tile_index.csv` for placement and consistent height scaling (0–65535).

### Key Commands
- Refresh VRT: `gdalbuildvrt work/dgm.vrt raw_dgm1/*.tif`
- Run export pipeline: `python3 export_heightmaps.py`
- Inspect an output tile: `gdalinfo export_unity/height_png16/<tile>.png | head`

### Workflow Notes
- The script computes a global min/max from the VRT to scale all tiles consistently; adjust `OUT_RES`, `RESAMPLE`, or `TILE_SIZE_M` in `export_heightmaps.py` if your AOI or target resolution changes.
- `_tmp.tif` files in `work/` are transient; you can delete `work/` to force a clean rebuild.
- Keep file names stable to avoid churn in Unity scenes; re-exports overwrite in place.
- Large raw datasets are intentionally excluded from version control—document download sources or scripts instead of committing data.
- Additional inputs: `raw_dop/` contains an HTTPS download helper (`raw_dop/dlscript.sh`) that fetches JP2/J2W/XML orthophotos listed in `filelist.txt`; `3dgeblod1/` and `3dgeblod2/` hold zipped 3D building tiles with object lists for future use.
- Handoff to Unity: copy/sync `export_unity/height_png16/` and `export_unity/tile_index.csv` into `DTrierFlood/Assets/GeoData/` before running the Unity-side importer. Keep `OUT_RES` aligned with the importer’s expected resolution (currently 1025).

### Orthophotos (textures)
1. Ensure DOP JP2s are present in `raw_dop/jp2/` (use `raw_dop/dlscript.sh` if needed).
2. From `GeoData/`, run:
   ```bash
   python3 export_ortho_tiles.py
   ```
   This builds `work/dop.vrt` if missing and writes `export_unity/ortho_jpg/<tile>.jpg` + `.jgw` aligned to `tile_index.csv`.

### Buildings
The building export pipeline is temporarily disabled while we choose a mesh conversion approach (GDAL lacks a native OBJ writer). CityGML LoD2 sources remain in `raw_3dgeb_lod2/` locally (ignored in git); consider CityGML→glTF/OBJ tools (e.g., citygml-tools + cityjson2gltf) for future integration.