[mkgmap-dev] additional arcs patch

Sun Feb 23 12:43:17 GMT 2014

Hi WanMil,

thanks for testing. Today I found one more rule
in Garmin maps that we ignore when writing NOD
data. I have no idea yet if that is important or 
how to implement the rule.

Gerd

> Date: Sun, 23 Feb 2014 12:15:42 +0100
> From: wmgcnfg at web.de
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] additional arcs patch
> 
> I have compared results from the branch and the trunk.
> 
> I have to revert my suspicion: distances are equal.
> 
> I see some differences in routing so that it seems that larger roads are 
> much more prefered in trunk than in branch. I'll have to check if that's 
> good or bad :-)
> 
> WanMil
> 
> > Ignore the Google result.
> >
> > I am quite sure that there is a difference between the high-prec-coords
> > branch and the trunk. I need to recompile the map with the trunk to
> > confirm this.
> >
> > WanMil
> >
> >> Please, forgive my 2 cents on this:
> >>
> >> Depending on which projection each system is using, distance calculation
> >> may (and usually) differ by that much and maybe more.  As far as I know,
> >> Google uses a Mercator-like projection on a spherical Earth model, which
> >> is not correct since Google coordinates refer to the WGS-84 ellipsoid.
> >> So you can expect differences, greater with higher latitudes.
> >>
> >> So don't use Google as an accurate reference.
> >>
> >> all the best,
> >>
> >> Paulo
> >>
> >>
> >> 2014-02-20 17:23 GMT-03:00 WanMil <wmgcnfg at web.de
> >> <mailto:wmgcnfg at web.de>>:
> >>
> >>     Hi Gerd,
> >>
> >>     which difference do you expect regarding the indirect links? I want
> >>     to get an idea what I should check on my device.
> >>
> >>     I have compiled a map using the patch and it seems that distances
> >>     are slightly underestimated.
> >>     One example: The distance between Hambug, An der Alster and Munich,
> >>     Maximiliansplatz:
> >>     MapSource: 776km
> >>     Google Maps: 788km
> >>     Both use the same route.
> >>
> >>     I didn't notice it before.
> >>
> >>     WanMil
> >>
> >>         Hi all,
> >>
> >>         attached is a patch for r3065 in the high-prec-coord branch.
> >>
> >>         It should improve long distance routing, as it adds additional
> >>         arcs from minor roads to major roads (so called indirect links).
> >>         Maybe the improvement is only seen on the device.
> >>
> >>         It would be great to hear some test results (good or bad),
> >>         compared to trunk r3057 and compared to r3065.
> >>
> >>         A compiled binary is here:
> >>         |http://files.mkgmap.org.uk/__download/179/mkgmap.jar
> >>         <http://files.mkgmap.org.uk/download/179/mkgmap.jar>
> >>
> >>         |Gerd
> >>
> >>
> >>
> >>
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