[mkgmap-dev] Problem in AngleFixer?

Mon Aug 5 09:42:46 BST 2024

Hi Gerd

I'll need to look carefully at this code again.

ISTR the 46 degrees was to stop arcs getting into the same compact segment when
they shouldn't. My changes stopped a lot of incorrect turn instructions but
maybe there is still scope for the algorithm to look for the same road entered
and exiting in a straight line and try to preserve this by adjust other roads
more.

Noticed that, in the example, these are bike routes and it looks like the algo
ignores these.

Ticker 

On Mon, 2024-08-05 at 06:37 +0000, Gerd Petermann wrote:
> Hi all,
> 
> in a private email Thorsten Kukuk contacted me about wrong turn instructions a
> sharp angles.
> An example is the node https://www.osm.org/node/27550903
> 
> A route coming from South that follows the way
> https://www.osm.org/way/36138336 at this junction should NOT produce a turn
> instruction.
> A route that turns left SHOULD produce a turn instruction. 
> With current mkgmap it's vice versa and thus not OK.
> 
> I thnk the current code in AngleFixer.java is too agressive as it tries to
> enlarge the angles so that a compact format can be used to write the
> heading values of the arcs at the mentioned node. It does this by changing the
> heading values of both arcs with go to the north.
> 
> @Ticker: The code was introduced with your arcHeading_v2.patch, but maybe it
> existed before.
> Can you explain why the constant AngleChecker.SHARP_DEGREES is set to 46°
> instead of maybe 22.5° ?
> 
> Gerd
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