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<body class='hmmessage'><div dir='ltr'>Hi Felix,<br><br>I was referring to a different junction (Ristedter Hauptstraße / Scheunenbrink) but<br>I see that this small area seems to contain some good test cases :-)<br><br>Up to now I found one additional problem when looking for candidate junctions :<br>Before modifying angles (or adding new ways) the algo has to find out if the <br>OSM data already contains that alternative way and if that way allows the wanted<br>traffic. I guess that check can be done by looking at the lengths of the two arcs and<br>the existence of an arc between the destination nodes of the two arcs.<br><br>If you agree, I'd first like to finish the discussion about the existing code for <br>--adjust-turn-headings. I think the code and the option should be removed,<br>I think the current code is often changing data to the worse, and it is just good<br>luck when it fixes one of the "sharp angle" problems, it might as well create<br>one.<br><br>Gerd<br><br><div><hr id="stopSpelling">Date: Mon, 10 Aug 2015 09:04:47 +0200<br>From: extremecarver@gmail.com<br>To: mkgmap-dev@lists.mkgmap.org.uk<br>Subject: Re: [mkgmap-dev] What is the idea behind --adjust-turn-headings?<br><br><div dir="ltr"><div><div><div>Good Morning Gerd,<br>Well if there is a any way to "fix" those sharp angles like "Hokenbarg" / Zum Grunewald and maybe even Schützenstraße / zum Grunewald by adding a super short "highway junction" type of connecting road - that would be great for cycling/pedestrian maps.<br></div>Even more as such angles are much more common in the nature compared to inside urban areas (and there they are not mapping errors).<br><br></div>The first junction is so sharp - that no Garmin device will ever try to route over it (except with road-speed 0 or maybe 1) - it would simply rather make a big detour around other streets...<br><br></div>Felix<br></div><div class="ecxgmail_extra"><br><div class="ecxgmail_quote">On 10 August 2015 at 08:19, Gerd Petermann <span dir="ltr"><<a href="mailto:gpetermann_muenchen@hotmail.com" target="_blank">gpetermann_muenchen@hotmail.com</a>></span> wrote:<br><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex;">
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<div dir="ltr">Hi Felix,<br><br>in fact I wanted to look at this point on the todo list<br>"detect sharp angles at road junctions and either change the heading values or
add small arcs"<br>when I found out that adjust-turn-headings isn't doing what I expexted. <br><br>The img format stores the initial heading of an arc leaving a given node as well<br>as the so called final heading. I think the initial heading is used to calculate the<br>time penalty, the final heading is used to find out where the arc takes you.<br>Sharp angles between two nodes don't matter much, they will only increase<br>a value that measures how "curvy" a road is.<br>So, I think that we don't need extra points in the map, we just need other <br><br>I agree that sharp angles cause higher time penalties, so it would be good to <br>avoid them for maps which are only used by cyclists or pedestrians.<br>It also is plausible that the penalty depends on the road-speed.<br><br>I see two cases where we have sharp angles:<br>1) Two parallel highways connect at a juction, like here:<br><a href="http://www.openstreetmap.org/search?query=52.976941%2c8.842898#map=18/52.97694/8.84290&layers=T" target="_blank">http://www.openstreetmap.org/search?query=52.976941%2C8.842898#map=18/52.97694/8.84290&layers=T</a><br>or here:<br><a href="http://www.openstreetmap.org/search?query=52.973986%2c8.854225#map=18/52.97399/8.85422&layers=T" target="_blank">http://www.openstreetmap.org/search?query=52.973986%2C8.854225#map=18/52.97399/8.85422&layers=T</a><br><br>2) Mapping errors (?) like here:<br><a href="http://www.openstreetmap.org/search?query=52.944818%2c8.762379#map=18/52.94482/8.76238&layers=T" target="_blank">http://www.openstreetmap.org/search?query=52.944818%2C8.762379#map=18/52.94482/8.76238&layers=T</a><br><br>where the junction of way 26667180 and way 4526346 is mapped with a very sharp angle while <br>Bing shows a different situation. <br><br>I fear it will be difficult to separate these cases by algorihtm, but I think the majority of sharp angles is<br>like the ones in 1) and I don't see a need to fix those.<br><br>Any ideas?<br><br>Gerd<br><br><div><hr>Date: Sat, 8 Aug 2015 00:12:57 +0200<br>From: <a href="mailto:extremecarver@gmail.com" target="_blank">extremecarver@gmail.com</a><span><br>To: <a href="mailto:mkgmap-dev@lists.mkgmap.org.uk" target="_blank">mkgmap-dev@lists.mkgmap.org.uk</a><br>Subject: Re: [mkgmap-dev] What is the idea behind --adjust-turn-headings?<br><br></span><div><div class="h5"><div dir="ltr"><div><div><div><div>It's not so much about the instruction - but about the time penalties.<br></div>Try out some super sharp turns - with different road-speed. there will be like 2-3 minutes penalties... No turn should be sharper than 50-60° angle left if possible - else the routing really breaks down...<br><br></div>Best would be actually to create small artificial roads to make the turn less sharp... (actually 4-5 points are enough - and have most of that turn in the additional mid 2-3 points).<br><br></div>I think adjust turn headings helps there a bit (for bicycle/foot routing - cause actual streets usually don't have relly sharp turns as cars could not do it - but for trails/pathes really awful turns exist (awful for the Garmin algo)...)<br><br><br></div>In case of crossings with 5-6 ways - even a small artifical turnaround would be great....<br></div><div><br><div>On 7 August 2015 at 16:40, Gerd Petermann <span dir="ltr"><<a href="mailto:gpetermann_muenchen@hotmail.com" target="_blank">gpetermann_muenchen@hotmail.com</a>></span> wrote:<br><blockquote style="border-left:1px #ccc solid;padding-left:1ex;">
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<div dir="ltr">Hi Marko,<br><br><div><span>> >// also helps to produce a turn instruction when the main<br>> >// road bends sharply but the side road keeps close to the<br>> >// original heading<br>> <br>> Oh, that would seem to be applicable for a scenario where you have a <br>> grid of highway=residential, and among them a main road (say, <br>> highway=tertiary) that is going like zig-zag within the grid. Could it <br>> be that Garmin is not issuing a turn instruction in this case, when the <br> > main road consists of a single object (with a sharp turn in it)?<br><br></span>Do you have an example OSM id?<span><br><br>> <br>> AFAIR, there was another option for implementing support for <br>> through_route relations, in a case where a main road goes zig-zag <br>> through a village. Is it still present in the code base? Maybe it makes <br>> this case of --adjust-turn-headings redundant?<br><br></span>The evaluation of through-route relations is still in the code, I guess it still<br>works, but IIRC the tag is only rarely used.<br><br><br>I did a few more tests now (without --housenumbers for now).<br>I think the code for --adjust-turn-heading is somehow wrong, e.g.<br>if the calculated route is <br>entering the junction at node 1828873253<br><a href="http://www.openstreetmap.org/node/1828873253" target="_blank">http://www.openstreetmap.org/node/1828873253</a><br>from south going right will not not show a "turn right" instruction<br>when --adjust-turn-heading is used, but it does without the option.<br>Consequently, if the route goes straight on to way 171930600,<br>the instruction is "turn left onto Börtelsdamm" with and <br> no instruction without the option.<br><br>It seems that Garmin uses the "Continue on" instruction only on ramps.<br><br>Reg. ramps I found no positive effect with --adjust-turn-heading, I see the <br>same instructions but sometimes the calculated time is increased, probably <br>because the code increases the angle too much.<br>Maybe the option (and the code) is really obsolete since r3116 which introduced <br>the new routines for writing NOD data:<br><a href="http://www.mkgmap.org.uk/news/2014/03/19/announcement-version-r3116-is-a-major-u" target="_blank">http://www.mkgmap.org.uk/news/2014/03/19/announcement-version-r3116-is-a-major-u</a><br><br>Up to now I did my tests with real data, I'll try to create some test data to find out<br>if there is still a case where --adjust-turn-heading produces better instructions.<span><font color="#888888"><br><br>Gerd<br><br></font></span></div></div>
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