[Marble-devel] Re: Tile Creation

[Anders Lund]

Hi Torsten,

Thanks a lot for answering  :)

On Tirsdag den 1. marts 2011, Torsten Rahn wrote:
> Did you have a look at the "Create new map" Wizard in marble trunk?

No, only description and screenshots. It looks very cool though, but I think 
it does not cover my case, read on...

> Also
> 
> http://techbase.kde.org/Projects/Marble/CustomMaps
> 
> might be interesting.

I did read that, but it does not answer many questions.

Qeustions:

What is the meaning the zoom element and children in the dgml file (except 
from discrete, which is explained)?

How can a map image be dimensioned, and how is the zoom levels calculated?

What is the projection of the tiles? Can it be specified?

Working from existing map material, I would have to place my bitmaps on 
surface somehow, probably split onto different tiles. I need to know how to 
calculate the level to place them in, and how to place them precicely. 
Preferebly, they should be displayed so the zoom is starting 100% of the 
original bitmaps, to avoid blurring.

I assume I can map the level to the map size, like a 1:100.000 map image 
belongs to level N.

I assume there must be a mapping of geographical coordinage to a pixel 
coordinate in a specific level of a specific projection.

My idea is to try and display some naval maps in marble, raster maps from BSB 
sets. They are always drawn in mercator projection. Naval maps comes in lots 
of scales, and sets typically contains different scales, that would map to 
different zoom levels. And of course I do not have maps covering the whole 
planet. (Can I use the flat map as a base, for display where there is nothing 
else?) 

I'll CC this to the mailing list.

-- 
Venlig hilsen,
Anders