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

Mon Apr 26 07:55:16 BST 2021

Thanks Andrzej for the patch.
It produces better results in about 2/3 of cases, and worse in about 1/3 of
cases for resolution 23. So overall it's an improvement, and at least for
compiling contourlines I didn't notice a significant difference in compile
time. I could test this more in detail also against normal map data if
needed...
Using *--simplifyContoursEpsilon*= in phyghtmap helps a bit too, especially
for resolution 24. However it runs super slow. It's like 1-30 times as much
time, if not more (except for a value of 0.0 which is not changing the maps
at all, and just making the .pbf file 10% smaller).

This doesn't solve phyghtmap not using b-spline interpolation. That would
improve even more (at least up to resolution 23, for resolution 22 maybe
this patch matters more). In general if using 20m equidistance I feel in
most cases it's good enough to compile contourlines only starting from
resolution 23, much faster, less data just of course in very steep areas
problematic. For 10m equidistance however it kinda means also going for
resolution 24, else the improvement from 20m to 10m is more of a nuisance.

On Mon, 26 Apr 2021 at 03:41, Andrzej Popowski <popej at poczta.onet.pl> wrote:

> Hi Gerd,
>
> I don't observe any significant differences in compilation. But to make
> it more optimized, we can put SizeFilter before DouglasPeuckerFilter. I
> have attached a second patch here.
>
> There is a difference in results. See pictures with DouglasPeuckerFilter
> after RoundCoordsFilter and new version with DouglasPeuckerFilter
> before. This is for 22-bit resolution, so effects are probably more clear.
>
> --
> Best regards,
> Andrzej
>
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
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-- 
Felix Hartman - Openmtbmap.org & VeloMap.org
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