Gerd,

I have been looking at the split files. The bounds are, as you say in your explanation (1), adjusted slightly. For example, latitude 43.0 on the original tile becomes 43.06 on the split tile. This occurs on both tiles, so the lower tile will gain 0.06 deg in which it has no data, and the upper one will lose its data in this gap. 0.06 deg of latitude is several km, so this accounts for my gaps.

The moral is, don't split tiles which don't need splitting!

(Presumably this always occurs at the edges of split areas, but cancels out internally when the tiles come from one larger one.)

Thanks again for guiding me through to the explanation.

Roger

On 08/01/2013 19:07, GerdP wrote:

Hmm, sorry, I was wrong again :-(

If splitter finds a bbox in the input file, this bbox is used and all data
outside of the bbox is 
ignored (maybe not with --keep-complete=true ). Typically, nodes outside of
the bbox belong to
ways that have also nodes inside of the bbox.

So, the question is if we solve the problem if we ignore the bbox of the
input file or if we simply
copy the input file when it is small. 
Do you have the problem with --keep-complete=true?

Gerd



GerdP wrote

GerdP wrote

I see two possible reasons:
1) splitter creates a new bounding box which is aligned to 2048 garmin
units, it will 
"blow up" the original bbox if needed.
2) If the input file contains a bounding box, splitter doesn't copy data
that lies 
outside of this bbox.

Sorry, forget 2) 
Splitter calculates the bounding box in this way:
it starts with an empty bbox. 
if a bounding box is found in the input file, this is used to enlarge
splitters bbox
it enlarges the bbox for each node in the input file that lies outside of
the bbox

The result is reported in the line starting "Exact map coverage is "
The next line begiining with ""Rounded map coverage is " shows the bbox 
that is written to the output file.

If I got this right, mkgmap should not have a problem with that. If it
does, the 
problem should be fixed in mkgmap.

Gerd




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