[mkgmap-dev] resolution, level & levels

Thu Sep 13 22:41:09 BST 2012

On 13/09/12 16:16, John Aldridge wrote:
> Oh, thank you. So would it be worth amending the documentation for

> o level, to add...
>
> Note that if a level number is used which does not appear in the /levels/
> specification, then it is treated as the next larger (or should this be
> smaller?) level number which is present.

Yes the documentation could be clearer, but that is not quite what
is happening.

The statement "level 2" is the same as "level 0-2" which means
that the item will appear at levels 0, 1 and 2. It will disappear
after you zoom out to level 3 or further.

For resolution the default end point is 24 so "resolution 23" means
"resolution 23-24". It therefore appears at any level which has a
resolution of 23 or 24.

So for
   levels = 0:24, 1:22, 2:20, 3:18, 4:16

that just means level 0

but with
   levels = 0:24, 1:23, 2:22, 3:20, 4:18, 5:16

it includes levels 0 and 1, which is what you observed.

[The wiki also says that you have to write the numbers the wrong way 
round (resolution 24-23; level 4-2) that was true (a bug) at one time, 
but now you can write them in any order]

..Steve