# [mkgmap-dev] Curvy routing support: new function?

From Manfred Brenneisen ManneB at gmx.net on Tue Jul 1 22:00:57 BST 2014

```Hi WanMil,

you are very fast, thank you very much for this!
However I'm facing some expectations, log:
a/lang/String;)V
gonFinishHook.java:50)
ooksChain.java:79)
apDataSource.java:49)
ce.java:127)
at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:63)
at uk.me.parabola.mkgmap.main.Main\$1.call(Main.java:253)
at uk.me.parabola.mkgmap.main.Main\$1.call(Main.java:249)

(I have installed r3310 which works ok, and then replaced mkgmap.jar by your build)

I'm open to any suggestions for other logic. A curviness function can only be a virtual value, not physical. However it may probably sufficient to say, curviness=length()/distance(first_point, last_point)? May be I'm thinking too complex :-)

Cheers
Manfred

> Gesendet: Dienstag, 01. Juli 2014 um 22:32 Uhr
> Von: WanMil <wmgcnfg at web.de>
> An: "Development list for mkgmap" <mkgmap-dev at lists.mkgmap.org.uk>
> Betreff: Re: [mkgmap-dev] Curvy routing support: new function?
>
> Hi,
>
> I remember that it is on my Todo-List :-)
>
> So I performed a quick implementation following your suggestion. You can
> find in the attached patch so that you can play a little bit with it.
> (Attention: it is completely untested!!)
> You can find a patched mkgmap.jar at http://files.mkgmap.org.uk/detail/215.
>
> I think curviness should to be defined in a different way.
> 1. Calculate the distance of each point Dmiddle to the virtual line from
> first to the last point.
> 2. curviness()=standard mean(Dmiddle/(length to next point + length to
> previous point)
>
> I think this gives a better indication how curviness a road is. But it
> need to be implemented and tested later on :-)
>
> WanMil
>
> > Hi all,
> >
> > Garmin offers "curvy roads" preferences for their zümo 390 and 590 devices.
> > I'm thinking about creating motorcycle maps for old 200 series.
> > Might it be useful to integrate a curviness() function so that mkgmap can optimize for curvy roads too? It might also help do determine a better default speed for curvy roads for use with car routing.
> >
> > The curviness() value might be the overall absolute turning angle (in degrees) of a road segment divided by the segment's length.
> >
> >
> > Cheers
> > Manfred
> >
> >
> >
> >
> > Pseudo code might look like this:
> >
> > function curviness()
> > {
> > oldpoint=points(0)
> > foreach (point of a way segment as newpoint)
> >    {
> >    d_x=(newpoint.x-oldpoint.x)/360*40000000*COS(newpoint.x*PI()/180) //in meters
> >    d_y=(newpoint.y-oldpoint.y)/360*40000000 //in meters
> >    length+=sqrt(d_x**2+d_y**2)
> >    angle=arctan(d_y/d_x)
> >    d_angle=abs(angle-old_angle)
> >    sgn_x=sgn(d_x)
> >    sgn_y=sgn(d_y)
> >    if ((sgn_x*sgn_y*old_sgn_x*old_sgn_y)=-1 && (sgn_x!=old_sgn_x))  d_angle=pi-d_angle  // 180 degrees correction, otherwise north-south roads show strange results
> >    if (point>1) sum_angle+=d_angle
> >    old_angle=angle
> >    oldpoint=newpoint
> >    old_sgn_x=sgn_x
> >    old_sgn_y=sgn_y
> >    }
> > return sum_angle/length
> > }
> >
> > // perhaps simple multiplication is faster than 4 times sgn() functions?
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk
> > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> >
>
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```