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[mkgmap-dev] Getting rid of the 'Node in too many areas' warning.

From Scott Crosby scrosby06 at gmail.com on Thu Jun 10 20:17:06 BST 2010

This patch to the splitter that makes
this warning MUCH more rare. With this patch, I can split the entire
planet into 17219 areas with max-nodes=50000 resolution=14 without a
single 'too many areas' warning among the the first 25 of 68
passes. Without this patch, a max-nodes=500000 split has dozens of
such warnings.

This patch can also allow larger overlaps at a cost of more

The fix works by reordering the list of generated tiles. The trick is
that the real limit in the splitter is that a node cannot be in more
than 4 distinct areas PER PASS (A limit that remains unchanged with
this patch.) If a node occurs in 10 tiles, but no single pass contains
more than 4 of those tiles, everything works.   If there are still 'too many

areas' warnings, they can be handled by reducing --max-areas.

Note that my patch depends on some other bug fixes; there are several
infinite recursion bugs in the current code that trigger when having
the splitter generate such small tiles. Some of these were fixed in
the trunk, but not all are. In addition, my fixes/cleanups try harder
at getting a good split.

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