[mkgmap-dev] Rounding bug in splitter?

Thu Aug 13 00:10:21 BST 2009

Chris Miller wrote:
> Hi Valentijn,
>
>   
>> Chris Miller schreef:
>>
>>     
>>> but my impression is that the conclusion was that the splitter should
>>> be rounding areas off to boundaries in multiples of 4096 rather than
>>> 2048?
>>>
>>>       
>> As far as I've seen - thanks to Steve Ratcliffe's findings - divisible
>> by 2048 is enough, if you make sure that the difference is a multiple
>> of 4096. (i.e. if your bounds are 0x123800 and 0x456800, that is OK;
>> but 0x123800 and 0x456000 is not OK).
>>
>> Anyway, dividing by 4096 is a good method of achieving this.
>>     
>
> I've checked in what is hopefully a fix for this to the splitter. There's 
> a new parameter called --resolution, which represents the lowest zoom level 
> specified in your style file and dictates what boundaries to align the split 
> tiles on. By default it's 13 which equates to tiles on boundaries of 2048 
> map units, and tiles with width/height in multiples of 4096 units.
>   
the resolution option seems to be not working... I set resolution=15 but 
it defaults to 13.
 Actually if my lowest object is in resolution 16, meaning an empty 
level will be created at resolution 15, do I have to tell resolution=16 
or resolution=15? - I assume 16, but to be on the safe side just went 
for 15.....

Also since sometime the maxnodes seems to be disrepted, I noticed it 
this morning after updating from svn....

D:\Garmin\mkgmap>start /low /b /wait java -enableassertions -jar 
-Xmx1200M splitter.jar --mapid=63200000 --maxnodes=1000000  
--resoultion=15 switzerland.osm

/D:\Garmin\mkgmap>start /low /b /wait java -enableassertions -jar 
-Xmx1200M splitter.jar --mapid=63200000 /-/-maxnodes=1000000  
--resoultion=15 switzerland.osm /

/Time started: Thu Aug 13 01:03:10 CEST 2009
mapid = 63200000
maxnodes = 1000000
*resoultion = 15*
Map is being split for *resolution 13:*
 - area boundaries are aligned to 0x800 map units
 - areas are multiples of 0x1000 map units wide and high
Processing switzerland.osm
2.500.000 nodes processed...
A total of 2595381 nodes were processed in 1 file
Min node ID = 172204
Max node ID = 461905799
Time: Thu Aug 13 01:03:38 CEST 2009
Exact map coverage is (45.821378231048584,5.957551002502441) to 
(47.80904531478882,10.491621494293213)
Rounded map coverage is (45.791015625,5.9326171875) to 
(47.8125,10.5029296875)
Splitting nodes into areas containing a maximum of 1.600.000 nodes each...
2 areas generated:
Area 63200000 contains *1.277.171 nodes *(45.791015625,5.9326171875) to 
(47.8125,8.1298828125)
Area 63200001 contains *1.318.210 nodes* (45.791015625,8.1298828125) to 
(47.8125,10.5029296875)
Writing out split osm files Thu Aug 13 01:03:38 CEST 2009
Processing 2 areas in a single pass
Starting pass 1, processing 2 areas (63200000 to 63200001)
2.500.000 nodes processed...
Writing ways Thu Aug 13 01:04:24 CEST 2009
Writing relations Thu Aug 13 01:04:44 CEST 2009
Wrote 2.595.381 nodes, 269.182 ways, 2.463 relations
Time finished: Thu Aug 13 01:04:44 CEST 2009/

> I've tested this with the netherlands.osm map and can't see any obvious problems 
> (including around the tile borders and when routing across tiles), but as 
> this is the first time I've used mkgmap to load osm files into MapSource 
> I'm not 100% sure what I'm supposed to be looking for and your testing and 
> comments would be appreciated.
>
> Have a play and let me know if you think it's an improvement.
>
> Cheers,
> Chris
>
>
>
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>   

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