[mkgmap-dev] [Patch v5] LocationHook with new Quadtree

Wed Jan 18 20:08:03 GMT 2012

Hi WanMil,

I have no special reason for using the nano second timer. I tried it because
I noticed that the mili second timer is very inaccurate. I got the
impression that nano seconds are more precise, but of course the only usable
value is a mean value of long running tasks.

ciao,
Gerd

WanMil wrote
> 
> Hi Gerd,
> 
> thanks for your further patch.
> I have a question about it: I see that you measure timings with nano 
> second timer. I am quite sure that such accuracy is not given in such 
> time measurements and often lead to wrong results. Do you really require 
> that accuracy? In such a case I am sure that you can stop coding because 
> there would be nothing more to improve so that the total runtime 
> decreases. It would be just a matter of fortune.
> 
> I think the only reasonable indicator is to measure the sum of the 
> overall LocationHook timing for several tiles (>20). If that decreases 
> significantly there is an improvement.
> 
> WanMil
> 
> 
> 
>> Hi WanMil,
>>
>> attached is the new version of the patch, now based on r2171.
>> I've invested a lot of time testing the result of LocationHook, I think
>> it
>> is always as good or better than trunk.
>> I will now try to add the quadtree to the preparer.
>>
>> Changes:
>> - build.xml with includeantruntime="false" to calm down ant
>> - added a few debugging aids and printout of complete runtime
>> - performance improvements in add() and merge() methods
>> - if a search in the nodes of the quadtree doesn't find the area,
>> additional
>> searches are performed for points
>>    in the neighbourhood
>> - for ways, the mid point is searched first. If the search returns null,
>> all
>> points are searched from the first one until a result is found. With my
>> test
>> data, quadtree never returned null, so this last loop is probably only
>> needed when boundary data is very incomplete.
>>
>> http://gis.638310.n2.nabble.com/file/n7199763/locationHook_speedup_v5.patch
>> locationHook_speedup_v5.patch
>>
>> ciao,
>> Gerd
>>
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