[mapserver-users] Re: polygon border artifacts

[Sven Geggus]

"Lime, Steve D (DNR)" <Steve.Lime at state.mn.us> wrote:

> Do outlines fix things at all zoom levels?

Not really. The Workaround which is working best for now is using a very big
polygon Overlap of 100Meters (Talking about Google Mercator here) which I
feel is way to much and an outline with of 1. To completely get rid of
artifacts I would need an Outline width of 2, but this is not small enough
IMO.

> What about the possibility of fixing the data?

The bug is clearly with mapserver here, the data is fine IMO. The tool used
for generation of the tiles does already allow for generation of arbitrary
overlap widths (https://github.com/joto/osmcoastline/).

> I mean, unioning the ocean polys into one, or better yet deriving land polygons from 
> that data.

No, unfortunately both of them are not an Option!

1. Unioning the polygons:
I presented a small shapefile just to demonstrate the problem.
The original file I want to use contains ocean tiles covering the whole
world. So this has been spitted into tiles for a reason!

2. Land polygons:
These are also not an option because I want to use the ocean tiles to
cover inaccurate hillshading derived from srtm. This will not work the other
way round.

The only thing I could imagine as a solution on the data side would be
the clipping of the hillshades by means of the polygon shape.

Regards

Sven

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