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!