[mkgmap-dev] resolution, level & levels

Thu Sep 13 15:32:41 BST 2012

Everything goes down to resolutions, but in the resolution / levels file 
in the style, you still need to define, which resolutions are actually 
input to the map. If resolution 23 is not actually a resolution that 
exists (as by default) - then 23 means it will only be put into 24.
On 13.09.2012 12:53, John Aldridge wrote:
> I'm confused about the way resolution, level and levels interact.
>
> I started with a set of supplied styles (actually from Marco Certelli's
> CreateIMG package) which used resolutions 14, 16, 18, 20, 22 & 24 for
> various kinds of roads. I wanted to change residential roads to come
> higher than tertiary roads (resolution=22) but lower than footways &
> tracks (resolution=24), so I changed them to be at resolution=23.
> Unfortunately this didn't work -- they appeared and disappeared at the
> same time as the the resolution=22 tertiary roads.
>
> I then changed the levels specification from the supplied
>
>    levels = 0:24, 1:22, 2:20, 3:18, 4:16
>
> to
>
>    levels = 0:24, 1:23, 2:22, 3:20, 4:18, 5:16
>
>
> and everything sprang into life working as desired. This behaviour was
> consistent between BaseCamp and my Oregon.
>
> The documentation in
>
>    http://wiki.openstreetmap.org/wiki/Mkgmap/help/style_rules
>
> had led me to think (though I guess it doesn't say so explicitly) that
> level & levels were meaningful only to the Mkgmap compiler, and were
> converted to resolution in the final Garmin format map files. As a result
> I was surprised that changing the levels specification had any effect at
> all, since all rules used resolution rather than level anyway.
>
> Could anyone shed any light on this behaviour? Thanks!
>