[mkgmap-dev] max-nodes in splitter

Sat Nov 12 09:05:37 GMT 2016

Hi Jakob,

Jakob Mühldorfer-2 wrote
>   * Does the splitter print an error when max-nodes is too large, or is
>     it unpredictable and will it only fail on the GPS device

No. There is no specific limit on the number of nodes in the device, the
value is just an easy to calculate number which expresses the density of
data. There are size limits in a single IMG file, and mkgmap will print an
error message (and write an empty img file) in such a case, so one wants to
avoid that. The actual tile size depends on various parameters, esp. the
style.

Jakob Mühldorfer-2 wrote
>   * Do tiles with more nodes mean higher or lower draw performance on
>     devices, or not matter at all

I have no idea. If you split an area into many small tiles instead of a few
larger ones, you will more often
cross the border of a tile when driving through the area, which probably
means that the device has to read the whole next tile. On the other hand,
reading a small tile should be faster. 
Within a single tile the data is again organized in smaller sub areas, so
the impact on draw performance should be very small.
I've looked at a few Garmin gmapsupp files and they have tile sizes between
2 and 12 MB, so Garmin seems not to care about it very much.

Gerd

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