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Last active March 23, 2024 10:55
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a_note_for_simon.md

Intro

Simon Willison as usual wrote a very interesting post:
https://simonwillison.net/2024/Mar/22/claude-and-chatgpt-case-study/

He had a linear shapefile of the Adirondack Park in the USA, composed of multiple lines. His goal was to transform these lines into a polygonal GeoJSON. The challenge was to create a continuous polygon that represented the park's boundary, as defined by the lines.

The article discusses the author's use of AI tools, Claude and ChatGPT, for a quick sidequest involving converting a shapefile to GeoJSON.

Here the direct and very simple ogr way to do it, simply using his beloved sqlite and its spatial extension.

The ogr way to do it

ogr2ogr -f "GeoJSON" output.geojson AdirondackParkBoundary2017.shp -dialect sqlite -sql "
SELECT ST_Polygonize(geometry) AS geom FROM AdirondackParkBoundary2017
" -lco RFC7946=YES

ogr2ogr: https://gdal.org/programs/ogr2ogr.html

The spatialite SQL functions reference list:
https://www.gaia-gis.it/gaia-sins/spatialite-sql-5.1.0.html

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