dashed boundaries are heavily affected by line geometry

[matkoniecz]

Straight borders render as expected, boundaries that are more complex render poorly

http://www.openstreetmap.org/#map=5/34.814/18.896

http://www.openstreetmap.org/#map=6/0.505/32.168

extracted from #1125 (coastline paradox)

[pnorman]

There's a couple of issues - one is the coastline paradox, the other is that ways may be split.

This may be unfixable with osm-carto. Normally I'd recommend using NE admin data for low zooms which makes solving these problems easier, but that's not an option for us.

[imagico]

A similar problem exists on somewhat different scales for intermittent waterways.

NE data is not really a solution since you only substitute one problem (too much detail) with others: It is not designed for mercator so it looks non-uniform at different latitudes and is not matching the other features shown in the map. You can see these problems in this style at z<4 where NE is used.

This is fixable but this comes with a number of problems:

• this style is very hesitant regarding use of preprocessed data, mostly for good reasons of course.
• there is relatively little interest and therefore limited resources are available for developing good solutions for these issues.

[kocio-pl]

We could use more simplification, like in #3103.

The problem is also reduced by #2834.