Map file format

[Andrey Novikov]

Ive read https://github.com/mapsforge/mapsforge/blob/master/docs/Specification-Binary-Map-File.md several times, but can not clearly understand how base zoom level works. Is only base zoom level stored in the file for each zoom interval? How are other levels created from base level? Just by splitting and combining?

[Emux]

Map file format could be a difficult area to master in Mapsforge.

See also past discussions in the forum for zoom intervals, e.g.
https://groups.google.com/forum/#!topic/mapsforge-dev/cdprA0-x5m0

Copying my words from there:
"Zoom level intervals during map creation declare the sub-files that the final map file will contain.
The base zoom is where the actual rendering happens and used above and below in the interval.
Sub-files are the internal structures holding the data separated per zoom group and simplification factor."

--
Emux

[Andrey Novikov]

So, all my assumptions are correct?

[Emux]

Yes and that's why to overcome the notorious artifacts issue in zooms 12-13 coming from base zoom 14 mesh, we need to provide an extra zoom interval:
5,0,7,10,8,11,12,12,13,14,14,21

--
Emux