[mkgmap-dev] Splitter

Sun Jul 27 08:17:58 BST 2014

Hi,

we have two conflicting goals in the splitter algo:
1) create tiles with a small aspect ratio (target : < 1:4)
2) create tiles with similar number of nodes

I have no idea which one is more important.

A few possible solutions for the tile which has 1.112.635 nodes and a height of 288, width of 89 grid units:
Vertical split at 269: 2 tile(s). The smallest node count is 23499 (4 %), the worst aspect ratio is near 3.92
Vertical split at 280: 2 tile(s). The smallest node count is 187764 (33 %), the worst aspect ratio is near 9.27
Vertical split at 284: 2 tile(s). The smallest node count is 503112 (90 %), the worst aspect ratio is near 18.5
Horizontal split at 79: 2 tile(s). The smallest node count is 528774 (95 %), the worst aspect ratio is near 30.91

Any idea? 
In the past, we tried to reduce the aspect ratio because routing over tile boundaries caused trouble.
Is that still important? Or is it just a cosmetic problem now?

Gerd

> Date: Thu, 3 Jul 2014 20:41:05 +0200
> From: osm at na1400.info
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: [mkgmap-dev] Splitter
> 
> There is a ~20MB o5m file that needs to be split. But Splitter returns:
> 
> "Cannot find a good split with exactly 2 areas"
> 
> I hope a (the) dev can have a look at this? Thanks!
> 
> The tile is here: 
> http://osm.pleiades.uni-wuppertal.de/garmin/20140703/63240007.o5m
> 
> See for more info and a link to the o5m file:
> http://forum.openstreetmap.org/viewtopic.php?pid=434024#p434024
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev

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