[mkgmap-dev] [PATCH] alpha patch for simplifying ways and reducing img size

Fri Feb 20 09:58:28 GMT 2009

Find attached an patch (usable on R915), which reduces the point density 
of ways and roads to reduce the filesize of the resulting img file.
It does it by using the douglas peucker algorithm. With this algorithm 
it is possible to set a max error distance and the resulting line will 
have filtered out all points without any points outside this distance band.
For an exact explanation consult wikipedia.

I tried it with an error distance of 10m. Higher distances don't gain 
much more.
The saving is in some areas with bad osm data (useless high point 
density) up to 25%.
In general it saves only 5% in file size.

Consider this patch as an alpha release, which should only show the 
possibilities.
For the release it will need at least an option at the commandline for 
setting the error distance.

Also I'm not sure, if the StyledConverter.java is the correct file for 
this patch. I've seen there is some filter infrastructure in the mkgmap 
project, but I've no idea how to use it.
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