[mkgmap-dev] [Patch v1] Don't write useless data to NET file

Sat Oct 12 10:52:34 BST 2013

Hi Steve,

seems that my idea was already tried with r909 in 2009, and Robert Vollmert wasn't 
happy with it:
http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2009q1/000776.html

I still try to understand what he means...

Gerd

> From: steve at parabola.me.uk
> Date: Fri, 11 Oct 2013 23:21:59 +0100
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] [Patch v1] Don't write useless data to NET file
> 
> 
> 
> 
> >@Steve: I assume that the Garmin maps contain also 
> >data for lower resolutions in NET, so maybe they also
> >have NOD data that points to this while we have not? 
> 
> I doubt that the data is useless, since that is how the maps are meant to be.  I do not know what it is for, but I would guess it would be only used on a GPS device and that it would have nothing directly to do with auto-routing, since it is NOD that controls that.
> 
> It could be just used as an optimisation, rather than being essential. Or it may not be used on modern devices. Anyway lots of investigation needed before declaring it un-used.
> 
> I've noticed that we only ever seem to have one road segment in one NET entry, whereas there can be more than one. (And I thought at one time there really was multiple segment combined.)
> 
> Having a single NET entry containing multiple road lines might help routing by reducing the number of entries in NOD
> 
> Of course if we are writing the wrong thing then that is kind of useless :-) and I would not be surprised if there were several bugs.
> 
> ..Steve
> 
> 
> 
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