[mkgmap-dev] question regarding MapRoad

Sat Oct 26 21:22:56 BST 2013

Hi Gerd

> Another question is whether we shoud try to put as many objects as
> possible into one subdiv. I could imagine that the device is happier
> if it finds more, but smaller subdivs. I think it is worth trying.

Yes all those things sound reasonable and worth trying.

Would be useful to have a tool that can show or confirm how the
subdivisions and objects are lining up.

Do you know of the ImgViewer program:
   http://garmin-img.cvs.sourceforge.net/viewvc/garmin-img/ImgViewer/
It shows subdiv boundaries.

> Another interesting point: Empty subdivs.
> I don't see many of them in my Garmin map, but mkgmap creates quite a lot.
> An empty subdiv is created when we split a subdiv into two equal halves,
> and all
> data is in one half.  It is quite simple to change the current algo to
> split again at a different position so that both parts  contain more or
> less the same amount of data.

Yes I believe that empty subdivs can be removed at least for the
highest resolution.  They are chained between levels, so you can
probably remove any empty subdivision that does not have any non-empty
child subdivisions too.

This makes a big difference if you have a large mostly empty map such
as over an ocean.

..Steve
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