[mkgmap-dev] [Patch v1] avoid wrong bearing results

Thu Oct 31 21:44:31 GMT 2013

Hi Marko,

the patch (this v1) is only meant to solve routing problems caused 
by rounding  I don't think that it has an influence on SeaGenerator.
It is possible that it increases NOD size a little bit.

Do you have a reason for not using precompiled sea?

Ciao,
Gerd

> Date: Thu, 31 Oct 2013 21:36:54 +0200
> From: marko.makela at iki.fi
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] [Patch v1] avoid wrong bearing results
> 
> On Thu, Oct 31, 2013 at 10:08:53AM -0700, GerdP wrote:
> >a few weeks ago I suggested that we might need higher precision in the
> >Coord class.
> >
> >Attached patch is a quick hack to implement this.
> >If I got it right, this may allow to remove a lot
> >of code that tries to correct what the rounding had
> >done wrong. For the beginning, I've used the
> >precise values only for bearing calculations,
> >as I think that this is most important.
> >
> >high_precision_coord_v1.patch
> ><http://gis.19327.n5.nabble.com/file/n5783533/high_precision_coord_v1.patch>
> >
> >Please let me know what you think about it.
> 
> This sounds interesting. I tried it out on finland.osm.pbf, wondering if 
> it would make some of the bogus warnings for anti-islands go away.  
> (There are some very tiny islets or rocks mapped as natural=coastline.)
> 
> I guess, it is to be expected that your patch does not yet fix bogus 
> warnings about the direction of hyper-precisely mapped roundabouts or 
> tiny coastline polygons. Here is an example that I got with your patch:
> 
> 2013/10/31 21:16:32 WARNING (SeaGenerator): 63240002.osm.pbf: Converting 
> anti-island starting at 
> http://www.openstreetmap.org/?mlat=60.21780&mlon=25.30937&zoom=17 into 
> an island as it is surrounded by water
> 
> This is http://www.openstreetmap.org/browse/way/241289746, a tiny islet, 
> properly mapped in counterclockwise direction.
> 
> For some reason, current svn head (r2795) with your patch is producing 
> more error messages than the revision I used earlier (I guess r2640).  
> With the old mkgmap, I got 545041 bytes of log, and with the patched 
> r2795, I got 774890 bytes, for the same input. The map sizes grew too:
> 
>   Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
> 142065664  Defl:X 113283124  20% 2013-10-31 05:23 05eede3d  gmapsupp.img
> 143736832  Defl:X 114490132  20% 2013-10-31 05:23 662f2ea9  gmapsupp.img
> 
> (The timestamp is that of the finland.osm.pbf file.)
> 
> Best regards,
> 
> 	Marko
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