[mkgmap-dev] Testing inter-tile routing with mapsource

Fri Feb 27 21:44:35 GMT 2009

>> When zooming out to, e.g. all of Germany, a cgpsmapper map is drawn very
>> fast by my eTrex. A mkgmap map takes a much longer time. Both show
>> motorways only. Perhaps there is really less data in the zoomed out tiles?
>>     
>
> 2. Staircase lines in the outer zoom levels.  This is where smoothing would
>    be really welcome.  I think (I could be wrong) that at the high zoom
>    levels you will have to join the different parts of a road up before
>    smoothing them (or something that has the same effect).
>   
I'm trying this at the moment, but it destroys my map. Seems to have 
some bug in it. Could it be a problem with some linking of nodes to ways 
pointing to the original way?
> 3. Motoway ramps.  I guess we can leave them out at outer zoom levels if
>    it doesn't affect routing.
>   
This is my opinion too. This should also be achieved by setting a 
reasonable MIN_SIZE. See below.
> 4. Lakes, forests at outer zoom layers.  We should have a way of leaving
>    out smaller polygon features at outer zoom levels, while leaving in
>    the larger ones.
>   
This should be possible already with the MIN_SIZE in SmoothingFilter. 
Maybe neccessary to set different values for lines and polygons.
(Btw. In a previous patch I have extracted this code to a separate 
SizeFilter.)

If you set a MIN_SIZE=1 it nearly doubles drawing speed on my etrex in 
the lowest zoom levels.