Hi Gerd,
Hi,
I try to understand the implementation of the code that creates the road net work. In 2009 Mark Burton implemented a feature using tags like mkgmap:road-speed in the points file. See http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2009q4/004777.html
Before that Mark also added a feature to handle points with an access tags like "access", "barrier", or "highway".
I think the code for these features is not correct, it sometimes splits roads into short arcs.
What the hell are short arcs? Everybodys talking about but I haven't understood so far... :-)
Questions: 1) If a road with road_speed=4 has e.g. 10 points (= OSM nodes) , and the 3rd point has tag mkgmap:road-speed=-1 and the 8th point has tag mkgmap:road-speed=+1, what is the expected result? I would assume that the road is split into 3 parts, one containining points 1-3, one the points 3-8, and the last one the points 8-10. The 1st part would use the unchanged road_speed value 4, the 2nd part the the value 3 and the last part the value 5. (if this doesn't introduce any short arcs, else splitting makes no sense for these tags) Correct?
Having a look at the code I would expect part uses points 1-4, part two uses points 4-9 and part 3 9-10. The code splits at i+1: Way tail = splitWayAt(way, i + 1); What do I expect? Hhhm, not easy to say. The current splitting does not make much sense to me. Having a mkgmap:road-speed=-1 at point 3 of 10 lowers the speed until the 4th point. Reversing the way lowers the speed of the last 7 point (4-10). So the effect of mkgmap:road-speed on a point is quite random. So I would expect that mkgmap:road-speed=1 cuts out point 2-4 with lowered speed or it cuts out +-20m to have a cleary defined effect.
2) If a road with 10 points and access=foot has a 3rd point with barrier=bollard, should this cause a split of the road so that points 3-10 have access=bicycle? I think no.
Me too. See my comment to 1. I expect that a small area (+-1 point or +- x meter) around barrier=bollard uses access=bicycle.
3) If a road with 10 points and access=bicycle has a 3rd point with barrier=cycle_barrier, should this cause a split of the road (which just seems to increase the img size) ? I think no
This leads to the question: is barrier=cycle_barrier passable for cyclists? The wiki does not state this clearly. I guess the barrier handling should be updated because its implementation is quite old and the tagging maybe has changed or diversified since then. WanMil