[mkgmap-dev] splitter maximum tile size

Sat Dec 1 09:37:41 GMT 2012

Hi WanMil,

I think the maximum values should be as large as possible. When splitting planet, we have a huge tile covering 
an area in the pacific, this tile has almost no nodes. If splitter has to create tiles with max. 20 degrees width
we probably see tiles without nodes.

Gerd

Date: Fri, 30 Nov 2012 18:18:02 +0100
From: wmgcnfg at web.de
To: mkgmap-dev at lists.mkgmap.org.uk
Subject: Re: [mkgmap-dev] splitter maximum tile size

> Thorsten Kukuk wrote
>>>
>>> No, there is no limit for the maximum tiles size for now. Thanks for the
>>> hint.
>>> What is the limit? I guess it is not a constant, but depends on
>>> resolution
>>> and other
>>> values? Unfortunately the test data is gone and I didn't download it.
>>
>> If you want to look at the problem, I can try to regenerate the
>> data again.
>
> I am not sure if the problem has to be solved in splitter or in mkgmap.
> Anyway, please try to reproduce it.
> I also like to know why mkgmap has problems with tiles that contain only
> very few nodes. Or is it the gps device that has problems?
>
> Gerd

I played a little bit with a small testfile how large a tile can be. The 
attached test file has the maximum size which works for me:
  <bounds minlat="0.0" minlon="0.0" maxlat="85.0" maxlon="179.98"/>
Larger bounds cannot be put into a single tile.

For large tiles mkgmap requires much memory problem if the bounds 
parameter is set. They need to be completely loaded with a high memory 
consumption.

I don't know if there is a hard limit for the tile bounds size. Maybe 
using some limits in splitter for the maximum latitude and maximum 
longitude size would remove some problems, e.g. max lat = 20, max long = 20.

WanMil

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