Missing parts on rivers

Impacted Features/Layers

Long rivers like the "Elbe" or "Danupe" are kind of cluttered on low zooms (~7). This also happens in various other places/rivers.

Screenshots

High Zoom (~8)

Low Zoom (~7)

My thoughts on the issue/solution:

I suspect that the reason for this issue comes from the complex relations within OSM dataset, which splits it into multiple polygons. I am not really into the planetiler framework, but I think it would make sense to add some relation management for rivers/streams/canals/riverbanks and combine into MultiPolygons in post-process.

I would appreciate it if someone could me give me some feedback on my thoughts and a brief overview of how the relations should be implemented. I would be happy to implement this, but I failed so far.

Start by reproducing the missing or cluttered river parts around zoom levels 7–8 using the Elbe or Danupe examples and then investigate how Planetiler handles the related OpenStreetMap river, stream, canal, and riverbank data. Done means the affected long rivers render continuously and without the reported clutter at low zooms, with relation handling validated against comparable cases.