voxcity.downloader.gsiΒΆ

Module for downloading bare-earth DEM (Digital Terrain Model) tiles from the Geospatial Information Authority of Japan (GSI / ε›½εœŸεœ°η†ι™’) and converting them into a VoxCity-compatible georeferenced GeoTIFF.

GSI publishes elevation tiles on the standard XYZ Web-Mercator tile grid at https://cyberjapandata.gsi.go.jp/xyz/{type}/{z}/{x}/{y}.txt. Each tile is a 256x256 grid of elevation values (meters) as CSV text, with e marking no-data. Resolutions, finest first: dem5a (5 m laser, z15), dem5b (5 m photo, z15), dem10b (10 m nationwide, z14).

The mosaic is written natively in EPSG:3857 (no resampling); the downstream create_dem_grid_from_geotiff_polygon reprojects from the file’s own CRS.

Example

>>> verts = [(140.09, 36.21), (140.12, 36.21), (140.12, 36.24), (140.09, 36.24)]
>>> save_gsi_dem_as_geotiff(verts, "dem.tif")

FunctionsΒΆ

save_gsi_dem_as_geotiff(rectangle_vertices, filepath)

Download GSI bare-earth DEM for an ROI and save an EPSG:3857 GeoTIFF.

Module ContentsΒΆ

voxcity.downloader.gsi.save_gsi_dem_as_geotiff(rectangle_vertices, filepath, dem_type=None, nodata=GSI_NODATA, sleep=0.4, timeout_s=10, include_dem10b_fallback=True)ΒΆ

Download GSI bare-earth DEM for an ROI and save an EPSG:3857 GeoTIFF.

Parameters:

  • rectangle_vertices – list of (lon, lat) tuples defining the ROI.

  • filepath – output GeoTIFF path.

  • dem_type – None (default) to build a seamless mosaic by overlaying the finest products available per pixel (see below), or one of β€˜dem5a’ / β€˜dem5b’ / β€˜dem10b’ to force a single product with no merging.

  • nodata – no-data fill value.

  • sleep – seconds between requests (politeness; set 0 in tests).

  • timeout_s – per-request timeout.

  • include_dem10b_fallback – when auto-merging, backfill pixels covered by neither 5 m product with dem10b (10 m). Set False to leave such pixels as no-data.

Returns:

The written filepath.

Note

With dem_type=None the ROI is composed at z15 from dem5a, with dem5b filling any dem5a no-data pixels, and (optionally) dem10b filling whatever remains. This produces a seamless terrain even when the ROI straddles a dem5a coverage boundary, instead of leaving no-data holes. dem5b is fetched only for tiles where dem5a is incomplete, and dem10b only when 5 m no-data pixels remain, so fully dem5a-covered ROIs incur no extra requests. dem10b (z14) is half the resolution of the 5 m products; because both grids share the global mercator origin and differ by an exact power of two, its pixels are mapped without resampling artifacts.

Raises:

ValueError – if rectangle_vertices is empty, dem_type is invalid, or no tiles cover the area.