VTM MultiMapDatabase deduplication like Mapsforge MultiMapDataStore

[demiantres]

Hi,

The VTM MultiMapDatabase generally works fine but sometimes there are problems with areas defined in different map files (it looks as if the areas are completely removed/clipped away).

Does the VTM implementation include deduplication mechanisms, similar to the old Mapsforge MultiMapDataStore.DataPolicy (https://github.com/mapsforge/mapsforge/blob/master/mapsforge-map/src/main/java/org/mapsforge/map/datastore/MultiMapDataStore.java)? The MultiMapDatabase contains methods with a deduplication parameter (for instance MultiMapDatabase .readLabels) but I see no way how to use them.

Regards,

[devemux86]

About overlapping polygons in OpenGL, see #224 and #806 (comment).

I have not transferred Mapsforge's multi map data policy in VTM (see #208),
as VTM works differently with ITileDataSink instead of MapReadResult.

Mapsforge's RETURN_FIRST has empty areas and DEDUPLICATE was slow.

"DEDUPLICATE: the data from all files will be returned but duplicates will be eliminated. This is suitable when multiple maps cover the different areas, but there is some overlap at boundaries. This is the most expensive operation and often it is actually faster to double paint objects."

[demiantres]

The patch from #806 works pretty well.

[devemux86]

The patch from #806 works pretty well.

It also has empty areas.

[demiantres]

Good to know. But the overall look of the maps is better than without the patch.

[devemux86]

If you can make it work properly,
I can include it via a parameter in MultiMapFileTileSource.

It may need a larger data type for the hash (long, double, ...)
and probably adding more MapElement fields in the hash.

[devemux86]

mapsforge/mapsforge#1288 optimizes the deduplication of multiple maps in Mapsforge.

[devemux86]

#903 #905 provide in VTM:

• Mapsforge: deduplicate maps
• Fix overlapping map regions