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

From WanMil wmgcnfg at web.de on Wed Jan 18 19:36:13 GMT 2012

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.


> 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
> --
> View this message in context: http://gis.638310.n2.nabble.com/Patch-v5-LocationHook-with-new-Quadtree-tp7199763p7199763.html
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