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[mkgmap-dev] Idea for minor speed improvement for boundary preprocessing

From Gerd Petermann gpetermann_muenchen at hotmail.com on Thu Feb 23 20:52:08 GMT 2012

Hi WanMil,

> Date: Thu, 23 Feb 2012 21:38:47 +0100
> From: wmgcnfg at web.de
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: [mkgmap-dev] Idea for minor speed improvement for boundary	preprocessing
> Hi Gerd,
> boundary preprocessing takes quite a lot of time. That's not a big 
> problem because it's performed only by some people who publish their 
> results.
> But I think some speed improvements would not be bad anyhow?!

Well, at least for me it is ;-)

> While preprocessing asia and america I go an idea. The area of a 
> boundary is splitted into the raster. But each time the complete area is 
> intersected to the raster. In case an area is big and/or complex 
> (boundary of russia, USA, canada etc.) this takes a long time. It would 
> be possible first to cut the area into smaller pieces (columns or rows 
> of the raster) and then do the final cut to the raster. Maybe this saves 
> time because the column or row areas should be less complex.
> What do you think?

I think you are right and it should be easy to do. We just have to 
replace BoundarySaver.splitArea()  by a another quadtree with a big bbox.
I'll try it.

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