Rivers with islands not rendering correctly

[Robert_Hutton]

I’ve spent a fair bit of time working on the Anglesea area, mapping the entire town, but I can’t seem to get the river to render correctly.

http://www.openstreetmap.org/?lat=-38.40066&lon=144.18533&zoom=16&layers=B000TTF

Mapnik and osmarender each have different problems with it; mapnik fails to render the water blue, and osmarender fails to render the islands.

I notice that there’s a similar mapnik problem on the (for me) canonical river example, the Thames:

http://www.openstreetmap.org/?lat=51.48699&lon=-0.24884&zoom=15&layers=B000TTF

The above renders correctly at that zoom level, but incorrectly the next zoom level in.

Any ideas on what’s the best workaround? Making the river out of more, smaller areas that trace around the islands so that the islands aren’t fully enclosed by an outer water area? Changing the tags? I’m pretty sure the ways are going in the correct directions. Any ideas appreciated, otherwise I’ll just try fiddling with it before next wednesday’s mapnik render.

Thanks,

Robert.

[Erik_Lundin]

Tagging of riverbanks is described here. From my point of view there is no use of island=yes. What you need is

• closed way to describe the outer riverbank (water on the right), tagged with waterway=riverbank
• closed ways to describe the islands (water on the right), tagged with waterway=riverbank
• possibly the additional tag natural=water on the ways (don’t think the rendering will work otherwise, although it should)
• a relation between the ways (key=type, value=multipolygon, role=inner|outer)

An example can be found here.

Btw, you should consider adding layer=1 to the bridges.

[Robert_Hutton]

Thanks for the reply.

@Erik Lundin

Tagging of riverbanks is described here.

Yeah, I tried to follow that. Once I get this down pat I think I’ll edit the wiki page to make it clearer.

@Erik Lundin

From my point of view there is no use of island=yes.

Removed.

@Erik Lundin

What you need is

• closed way to describe the outer riverbank (water on the right), tagged with waterway=riverbank
• closed ways to describe the islands (water on the right), tagged with waterway=riverbank

Had that right at least.

@Erik Lundin

• possibly the additional tag natural=water on the ways (don’t think the rendering will work otherwise, although it should)
• a relation between the ways (key=type, value=multipolygon, role=inner|outer)

Done.

@Erik Lundin

An example can be found here.

Btw, you should consider adding layer=1 to the bridges.

Done.

Thanks, we’ll see if this fixes things!

[Erik_Lundin]

No problem

Just corrected a typo (multipoligon → multipolygon) and requested a rerender of the t@h. Let’s hope for the best now.