[mkgmap-dev] Fun with splitter tile descriptions

Sat Sep 12 13:55:09 BST 2009

Many thanks Johann, I'll take a look. I don't mind that the patch won't apply 
to the current splitter, it was more the logic you had used to sanitise the 
is_in values that I was interested in seeing since I imagine it took a bit 
of effort to get "right" :)

As an aside for anyone who's interested, here's a copy of the planet with 
tiles that have been named using the cities15000.zip GeoNames file (and max-nodes=1600000):

http://maps.google.co.uk/maps?q=http:%2F%2Fredyeti.net%2Fosm%2Fplanet-named.kml

Regards,
Chris

JG> Yes, thats true. As far as I can remember, the is_in tags was very
JG> inconsistent. But I had hoped my algorithm is flexible enough to
JG> ignore
JG> this inconsistency. The idea was to extract each name at each level
JG> of
JG> the is_in tag. So if I take for example is_in =
JG> Germany,Bavaria,Munich,suburb,street name,.... then I will count the
JG> frequency of all five words. With statistical probability Germany
JG> will
JG> be the most used word in this tile.
JG> Afterwards I try to find unique names for the tiles. The name
JG> Germany
JG> will be occur in nearly all tiles, so it is not unique and will not
JG> be
JG> used. Also the region Bavaria will be in more then one tile and will
JG> not
JG> be used. If the city Munich is contained fully in one tile, the name
JG> will get taken, otherwise I will go down to the next. So I will get
JG> the
JG> most used name which is unique for this tile.
>> If you do have some code that deals with filtering/sanitising the
>> is_in data I'd be interested to see it however as it sounds like it
>> would be worth investigating further.
>> 
JG> Find attached a patch, which works against the relative outdated
JG> R37. I've tried to update to the recent splitter, but it wont work.
JG> There was some structural changes from SubArea to Area.
JG> 
JG> Regards,
JG> Johann