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[mkgmap-dev] Distorted lines

From Felix Hartmann extremecarver at gmail.com on Fri Sep 20 08:52:35 BST 2013

I noticed that remove-short-arcs=5.4 can in some cases even break 
routing, remove-short-arcs on default (I think 2.8) is fine though. I 
could well believe there are some fundamental flaws in it, especially in 
combinaton with reduce-point-density (--reduce-point-density=3.4 

Maybe remove-short-arcs may not be bigger than the reduce-point-density 
On 20.09.2013 09:47, Gerd Petermann wrote:
> Hi Andrzej,
> I think there is no way to avoid the rounding errors caused by the 24b 
> bit limit, but
> some problems are definetely caused by the short-arc-removal routine which
> merges nodes which are too close.
> The weakness of the algo is that it doesn't care about the 
> "importance" of a road
> nor about the effect on straight lines.
> I will need a few days to dig into this again.
> Gerd
> Date: Sun, 1 Sep 2013 03:48:17 +0200
> From: popej at poczta.onet.pl
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: [mkgmap-dev] Distorted lines
> Hi,
> I observe badly looking lines. I have attached some pictures and xml
> objects that doesn't look good on Garmin map.
> My guess is that there is no proper simplifications for resolution
> 24bit. Points too dense are removed in a non optimal way which can lead
> to jagged curves. This could be the reason for bad looking tram railways
> (file tram1.osm in test.zip).
> Other reason could be removing of short lines. I think in this case some
> nodes are moved. It looks like instead of creating a new node in a
> middle of removed line, first point is used. This can lead to bigger
> distortion. This is probably the case of road example (file road1.osm).
> -- 
> Best regards,
> Andrzej
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