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[mkgmap-dev] Garmin uses overlapping tiles

From Andrzej Popowski popej at poczta.onet.pl on Tue Feb 6 13:57:07 GMT 2018

Hi Gerd,

I have some questions.

Is TRE area bigger than DEM area or tiles overlap but still DEM area is 
bigger than TRE? It looks like overlap is 4 Garmin's units, this is less 
than DEM raster size.

 > The next interesting point is that the 0x4a polygons of these two
 > tiles do NOT overlap.
 > They seem to share  768896 (!).

Is it a typo? I guess: polygon 0x4B and 768856

Does map data overlap too, or this is only extended rectangle size 
written to TRE header? If backgrounds don't overlap, maybe real map data 
don't either. If I get border value right, than maybe tile is extended 
only at left and top border?

What about routing nodes, if splitter creates overlapped tiles? I think 
there should be an external routing node where road crosses tile border. 
There would be mismatch, if tiles overlap.

Best regards,

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