[mkgmap-dev] Maps crashing Mapsource in big cities

Fri Feb 12 15:17:32 GMT 2010

FH> The problem seems to me, that if a tile has more max-nodes, then a
FH> very
FH> dense city (like Athens, Melbourne, ...) in an otherwise rather
FH> empty
FH> area (huge tile) will crash. For Athens I had to go as low as
FH> 600.000,
FH> for Melbourne 800.000 was fine.
FH> 1.600.000 is definitely not only crashing a few tiles, but in my
FH> eyes
FH> around 10% of European tiles.

One thing that is clear is that the limiting factor isn't really the number 
of nodes in a tile; more likely it's limited by the number (and type?) of 
ways or relations, or some combination thereof. This is a very difficult 
(expensive) calculation to perform however when trying to determine where 
the tile boundaries should fall, so the number of nodes is used as a fairly 
rough approximation instead. Of course even if there was an efficient way 
to subdivide based on way/relation counts, we still don't currently know 
what the rules should be that determine the limits for each tile.

Chris