[mkgmap-dev] mkgmap-dev Digest, Vol 153, Issue 40 Resolution 23 raster problems

Wed Apr 28 03:50:31 BST 2021

Thanks for that patch, the improvement is not as big as from the previous
patch - but there is some.
I analysed it a bit more - and I think there needs to be one more change -
actually in general and not only for contourlines.

We need different values for the douglas peucker algorithm depending on
resolution!

Right now we can only set one value, and that is multiplied for each
resolution?
Based on the current state I would like to have

resolution
24= 0.0 or maybe actually have it active at 24 as well trying a value of
0.3 or so. Where there any problems with autorouting or why is it not
possible to use it at resolution 24 as well?
23=1.3
22=2.6
21=3.9
20-11=5.4

Especially if we produce a map without resolution 24, then resolution 23
needs to have much lower DP value than the subsequent resolutions. Using
1.3 for resolution 23 makes the quality IMHO good enough to be used for an
contourlines only map for GPS devices and skipping resolution 24
altogether. For Desktop use resolution 24 may still make sense for
contourlines - but even then the difference is only in very steep areas.

Attached some screenshots at resolution 24, and at 23 with different DP
values and one of patch2.

On Tue, 27 Apr 2021 at 23:16, Andrzej Popowski <popej at poczta.onet.pl> wrote:

> Hi,
>
> some more experiments, see attached patch. I have tried to optimize
> rounding of coordinates for lowest distance to line. This is not good
> for polygons, because can creates gaps between adjacent polygons.
>
> --
> Best regards,
> Andrzej
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev

-- 
Felix Hartman - Openmtbmap.org & VeloMap.org
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