[mkgmap-dev] Problem in AngleFixer?

Mon Aug 5 19:14:00 BST 2024

Hi Gerd

I presume you are just changing SHARP_DEGREES, leaving COMPACT_DIR_DEGREES
alone.

In this example the arcs on either side of the sharp angle have the same
priority (class/speed) so there isn't an obvious one to adjust so the logic
adjusts both.

Also in this example, and very common, is a side turn off a basically straight
road and the proportions that each arc is adjusted isn't ideal in that the
straight road is bent slightly more than the side turn is adjusted.

This could be spotted as a special case: when there are 3 arcs and the available
angle on one side or the other (initial value of deltaPred or deltaNext) is
close to 180 degrees then just the other side should be adjusted. Maybe the 3
arcs doesn't really matter as long as there is sufficient space to adjust the
other side.

I'll do some experiments.

Ticker

On Mon, 2024-08-05 at 08:55 +0000, Gerd Petermann wrote:
> > > > Hi Ticker,
> > > > 
> > > > thanks, I didn't test much, but with a value of 22.5 (or 23) the problem
> > > > disappeared. It also disappears with
> > > > --x-ignore-sharp-angles. Downgrade is that the NOD size increases a bit,
> > > > but
> > > > I
> > > > think that is better than wrong turn instructions.
> > > > 
> > > > Let me know if you cannot reproduce and I'll create a more complete
> > > > description reg. the options in use.
> > > > 
> > > > ciao,
> > > > Gerd
> > > > 
> > > > ________________________________________
> > > > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> > > > Ticker
> > > > Berkin <rwb-mkgmap at jagit.co.uk>
> > > > Gesendet: Montag, 5. August 2024 10:42
> > > > An: Development list for mkgmap
> > > > Betreff: Re: [mkgmap-dev] Problem in AngleFixer?
> > > > 
> > > > 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
> > > > > > > > _______________________________________________
> > > > > > > > mkgmap-dev mailing list
> > > > > > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > > > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > > > 
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