kopia lustrzana https://github.com/openmaptiles/openmaptiles
4a1b0afa26
Instead of using [Douglas-Peucker algorithm](https://postgis.net/docs/ST_SimplifyPreserveTopology.html) which is using for generalized tables [imposm](https://imposm.org/docs/imposm3/latest/mapping.html#generalized-tables) it is used [Visvalingam-Whyatt algorithm](https://postgis.net/docs/ST_SimplifyVW.html). Solution: remove imposm generalized tables (during `import-osm`) and create generalization in `import-sql` step for zooms 7-14. Zooms 0-6 are from Natural Earth data. Upper zoom levels (7 and 8) are ok to merge with no big impact on creation speed. In Canada from z9 it took too long. Between zoom levels 10 - 13 there can be union polygons with less than 300 edge points (empirical number based on a test on Canada forest, can be discussed). Polygons with more than 300 edge points are just simplified. Zoom 14 is from the original dataset `osm_landcover_polygon`. There is also removed `osm_id` which is never used and not passed into vector tiles. |
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| .. | ||
| README.md | ||
| etl_diagram.png | ||
| generalized.sql | ||
| landcover.sql | ||
| landcover.yaml | ||
| mapping.yaml | ||
| mapping_diagram.png | ||
README.md
landcover
Docs
Read the layer documentation at http://openmaptiles.org/schema#landcover
Mapping Diagram
ETL diagram
