[mkgmap-dev] Still problems with remove-short-arcs

Wed Oct 30 18:01:15 GMT 2013

It fixes the routing problem for the reported roundabout, well done. I 
don't have any other test cases at this moment to test it further though.
Carlos

El 30/10/13 17:39, GerdP escribió:
> Hi all,
>
> attached is a patch that detects "wrong" angles in roundabouts and
> overwrites them with reasonable values.
> The typical angle in a roundabout is ~210°, it seems that Garmin
> likes values between 180° and 240°, and refuses to use other
> angles, at least on primary roads.
>
> Compiled binary based on trunk r2794 is here:
> http://files.mkgmap.org.uk/download/160/mkgmap.jar
>
> tweezeRoundaboutArcs_v1.patch
> <http://gis.19327.n5.nabble.com/file/n5783403/tweezeRoundaboutArcs_v1.patch>
>
> Note that this patch doesn't change the rendering data,
> so ugly roundabouts will still look the same.
> The corresponding patch is work in progress.
>
> Gerd
>
>
>
> GerdP wrote
>> Hi Carlos,
>>
>> just to clarify: You say that   remove-short-arcs=0 introduces the sharp
>> angle.
>> This is not true, as remove-short-arcs=0 will not move anything.  In fact,
>> the sharp angle is caused by the rounding to Garmin map units.
>> The green line in the screen shot shows the line that is used after
>> rounding. You see that the rounding introduces an angle of ca. 75°.
>> So why does rsa=3 help? Because it flatens the angle as it removes
>> one point. You can get the same effect if you move one of the node
>> 975733410 a little bit.
>> The problem disappears when I add a few lines in the code to make to sure
>> that the calculated bearings are closer to reality (means I overwrite the
>> values).
>> I thought that the check-roundabout or adjust-turn-headings options were
>> meant to do that, but they don't seem to help.
>> I think the reason is that adjust-turn-headings doesn't treat roundabouts
>> special.
>> I see two possible solutions when
>> we detect the situation that the rounding has created an angle which is
>> too sharp
>> to be reasonable in a roundabout:
>> 1) Overwrite the calculated heading values
>> 2) Try to find the point that was probably rounded wrong, and change its
>> coordinates. This would have to be done much earlier in the chain.
>>
>> Both will fix routing , but only 2) will help regarding the ugliness
>> of the displayed roundabout. I try to code option 2), maybe both are
>> needed because some roundabouts in OSM are divided into small
>> fragments.
>>
>> Gerd
>>
>> Date: Sun, 27 Oct 2013 19:09:43 +0100
>> From:
>> cdavilam@
>> To:
>> mkgmap-dev at .org
>> Subject: [mkgmap-dev] Still problems with remove-short-arcs
>>
>> I still get some wrong routing at some roundabouts using
>> remove-short-arcs=0. See attached screenshots.
>> At http://osm.org/go/b_YMZ7sDP-- MapSource makes a detour to avoid the
>> roundabout, due to a sharp angle that is introduced by
>> remove-short-arcs=0. If I use rsa=3, the route goes through the
>> roundabout, but the exit number is wrong, because the incoming road and
>> the first street are joined at the same node of the roundabout.
>>
>> _______________________________________________
>> mkgmap-dev mailing list
>> mkgmap-dev at .org
>> http://lists.mkgmap.org.uk/mailman/listinfo/mkgmap-dev 		 	   		
>> _______________________________________________
>> mkgmap-dev mailing list
>> mkgmap-dev at .org
>> http://lists.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>
>> carlos.png (151K)
>> &lt;http://gis.19327.n5.nabble.com/attachment/5783138/0/carlos.png&gt;
>
>
>
>
> --
> View this message in context: http://gis.19327.n5.nabble.com/Still-problems-with-remove-short-arcs-tp5783089p5783403.html
> Sent from the Mkgmap Development mailing list archive at Nabble.com.