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 --reduce-point-density-polygon=6). Maybe remove-short-arcs may not be bigger than the reduce-point-density values? 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@poczta.onet.pl To: mkgmap-dev@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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