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[mkgmap-dev] resolution, level & levels

From Steve Ratcliffe steve at parabola.me.uk on Fri Sep 14 11:23:16 BST 2012


> Thank you again. I think the fundamental thing I hadn't grasped was that
> you can't just put a resolution tag on something to cause it to be
> displayed at that resolution or greater, but that you have to in some
> sense "create" the level first with the levels specification before you

Thats right.  Each level can be thought of a completely separate

The levels command just tells the device which map to display at each
zoom. So for the following there are four maps:
  levels = 0:24, 1:22, 2:20, 3:18

The least detailed map (map 3) is displayed from zoom 18
and the most detailed (map 0) is displayed from zoom 24.

If you use 'level 1' then the feature goes into map 0 and map 1.
Whereas if you use 'resolution 22' then mkgmap has to use the 'levels'
parameter to work out which levels you mean and then it adds it to
appropriate map level. So using 'level' is more direct.

The other thing that you need to know is that a Garmin device
may just not display a POI if the resolution is too low.
So you may have it in the map at a given level, but if the device
does not want to display it at that resolution then it won't and
there is nothing you can do about that (as far as we know).


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