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Forum:Announcements/Beware FastDraw - Simplify

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ForumsOfficial announcements → Announcements/Beware FastDraw - Simplify


The OpenStreetMapW.svg FastDraw JOSM is very useful for drawing natural features, but it is really important to heed the warnings on that wiki page: "Please use simplification and validator! Do not upload huge and self-intersecting lines".

You should always run Simplify on the output, typically simplifying for at least 1m. If you don't then you add useless nodes to the OGF database, which result in needless storage and compute for evermore.

Uletha coastline node density

This is especially true for the twice hourly coastline validation process. It is very tuned, and uses a series of Overpass queries to inspect the coastline. These queries are greatly inflated by the unnecessary nodes.

Manual investigation the sqlite databases output by the coastline process can be used to pinpoint areas with very high coastline node density in QGIS:

  • Vector/Geometry Tools/Extract Vertices on land_polygons
  • Plugins/Density analysis/Geohash density grid on the vertices

/wangi (talk) 22:51, 4 February 2024 (UTC)