[OSRM-talk] Keep left and keep left and ...

Florian Lohoff f at zz.de
Sat May 8 14:46:52 UTC 2021


On Fri, May 07, 2021 at 09:36:34AM -0700, Brad Colbert via OSRM-talk wrote:
> Hello Everyone,
> 
> I'm working on modifying a profile.  Now when I run, the turn-by-turn has a
> ton of "Keep left at the fork" lines and I'm wondering why and how/if I can
> get rid of them.

Whenever you get announcements like this its unclear junctions e.g.
the angle of the roads split is the problem. You get an announcement
whenever the angle is greater than a certain default.

Most of the time its the OSM Data which needs fixing.

A couple years back i made a quick drawing to make the point:

https://silicon-verl.de/home/flo/tmp/osm-spitzer-winkel.jpg

On the left you see a typical OSM junction - When traveling
left to right you may hear a "keep left" on the left junction because
the angle is so great.

In reality junction are layed out like the one on the right. And
following the center line your angle is in most cases roughly 90° which
will cause no announcement when traveling across.

Announcements like this are caused by geometry or topology.

Flo
-- 
Florian Lohoff                                                     f at zz.de
  Any sufficiently advanced technology is indistinguishable from magic.
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