[mkgmap-dev] Problem in AngleFixer?

Tue Aug 6 11:26:37 BST 2024

Hi Gerd

Patch attached that, where possible, keeps ~straight roads unchanged and widens
the sharp angle on the other road.

This should fix the particular example and generally be better, although it is
difficult to test.

I try and note where I get incorrect turn instructions and later work out why
and, since the arcHeading_v2.patch in Oct 2020 I haven't found any that are
fixable; I couldn't find a solution where the major road continues at an angle
and the minor side road continues straight on.

Ticker

On Mon, 2024-08-05 at 19:14 +0100, Ticker Berkin wrote:
> 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
> > > > > 
> > > > > _______________________________________________
> > > > > mkgmap-dev mailing list
> > > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > > > > _______________________________________________
> > > > > mkgmap-dev mailing list
> > > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> 
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev

-------------- next part --------------
A non-text attachment was scrubbed...
Name: AngleChecker.patch
Type: text/x-patch
Size: 2562 bytes
Desc: not available
URL: <https://www.mkgmap.org.uk/pipermail/mkgmap-dev/attachments/20240806/2483c3f1/attachment.bin>