land_polygons layer creates "broken" tiles?

[jkempe]

I have noted issues with the layer land at zoom levels higher than 8, when we switch to osm.land_polygons. Tiles generated looks like the lack one corner of each split polygon. The problem is visible here:

I see the issue on both my instance (v0.5.0) and on osm.tegola.io

[ARolek]

@jkempe this is a simplification bug we're working on. The Douglas Packard algo does not play nicely nicely with right angles at that tolerance. A few issues / options to try / watch

• Turn off simplification: Check out DontSimplifyGeo under https://github.com/terranodo/tegola#environment-variables
• Plumb through simplification parameter to the config file
• Change out the simplification algorithm

The last bullet will hopefully produce the best results. Additionally you can turn off simplification after a certain zoom using the env vars in the first bullet. That's another near term option.

[ARolek]

This is now fixable using tegola v0.6.1 and setting dont_simplify = true on the following part of the config (updated in this repo):

[[maps.layers]]
name = "land"
provider_layer = "osm.land_8-20"
dont_simplify = true
min_zoom = 8
max_zoom = 20