Lake intersecting viewport is rendered wrong

[habi]

I'd like to produce a high-resolution render of a campsite and can do this by issuing map-machine render --boundary-box=6.712,46.802,6.723,46.807 --zoom=16 --output=out/vd8.svg.

This does render the lake bordering the campsite weirdly, e.g. glitches out with the intersection of the campsite. I know that rendering of lakes or larger water bodies is complicated, but how could I generate a nice map of this campsite?

[habi]

Some observations in relation to the lake rendering

• map-machine render --coordinates=46.805,6.715 --zoom=16 --output=out/bad0.svg
• map-machine render --coordinates 46.805,6.755 --zoom=16 --output=out/good0.svg
• map-machine render --coordinates 46.789,6.669 --zoom=16 --output=out/good1.svg
• map-machine render --coordinates 46.789,6.675 --zoom=16 --output=out/bad1.svg

At first I thougth it's because of the 'layering' of the lake with a swimming area also mapped there, but I now think it might have something to do with a wetland polygon in the vicinity.

[enzet]

Hello, @habi!

Thank you for the issue. I'm afraid, this is really a hard one. Map Machine downloads only ways that at least partly present inside boundary box, so it doesn't have enough information about lake shape.

I may provide two ways to fix that:

1. Easy one is to just try to download more data. I'll add an option to specify another bigger boundary box for downloading.
2. Hard one is to try to honestly compute lake shape analysing way direction.

I think, I want to start with the first one and then will continue with the second one.

[habi]

There's no option for 'discarding' a feature (the lake) in map-machine? Or could I somehow twiddle with the downloaded XML and try to remove all 'traces' of the lake?

[enzet]

Sure, you just need to either edit default scheme file or use a custom scheme file.

E.g. use no_water.yml and --scheme option:

map-machine render --coordinates=46.805,6.715 --zoom=16 --output=out/bad0.svg --scheme no_water.yml

no_water.yml is just map_machine/scheme/default.yml with the following diff:

   - tags: {natural: water}
     exception: {intermittent: "yes"}
     style:
-      fill: water_color
-      # stroke: water_border_color
-      # stroke-width: 1.0
+      # fill: water_color
+      stroke: water_border_color
+      stroke-width: 1.0
     priority: 21.0

[enzet]

This is a duplicate of #120.