crs-l1-nyc-webmercator-cycleways

Analyst notes

Description

Tests basic reprojection from Web Mercator (EPSG:3857) to WGS84 (EPSG:4326) on linestrings, with strict preservation of attributes and geometry type. Neither CRS is named, so the agent has to infer the source from the tile-renderer framing and the target from the request for plain lat/lon.

Approach

1. Read the input GeoParquet and inspect its CRS metadata.
2. Confirm the source CRS is Web Mercator (EPSG:3857).
3. Reproject the geometries to EPSG:4326.
4. Preserve every original column and keep each LineString as a LineString.
5. Write the result as GeoParquet to `nyc_cycleways_wgs84.geoparquet` with EPSG:4326 declared.

Pitfalls

• Missing the source CRS in the file metadata and reprojecting from a wrong assumption produces coordinates that are wildly off.
• GeoPandas or Shapely can silently turn single LineStrings into MultiLineStrings during the round-trip.
• Dropping or renaming the attribute columns means the renderer loses the metadata it needs.
• Writing the output in a different format like GeoJSON or Shapefile instead of GeoParquet leaves downstream tools unable to read it.
• Letting the CRS metadata get lost on write so EPSG:4326 isn't declared on the output file.

Map

Recent runs task v1