[mkgmap-dev] [PATCH] make gps report correct exit when routing through roundabouts

Wed Feb 11 22:32:58 GMT 2009

I have bad news and good news.

The bad news is that the second patch also failed.

The good news is that I *"think"* I have found the data that causes the
 problem. Call me sad if you want but I had a spare hour (not) so using
osmosis I started splitting the tile giving the error into 4 quarters. I
would run each of these and see if there were errors. I then split the
quarter with errors and repeated the process until I was left with the
attached file. In the bottom left quarter is a tiny roundabout. If you
just move the north node northwards and the south road southwards a
couple of feet then the tile runs without errors.

As it's such a minimal change I have already applied this to the live
map so this should be on the Geofabrik mirrir tomorrow. I'm out all day
tomorrow so won't be able to test this until the evening but I'll report
back as soon as possible.

Paul

P.S. This runs without the --frig-roundabouts option and runs on the
unpatched code from r877

Mark Burton wrote:
> Here's a new version of this patch.
> 
> What it does is an ugly hack but if it fixes the problem without hideous side effects it will probably serve until some better way of solving the problem is devised.
> 
> It is no longer enabled by default, you need to specify the --frig-roundabouts
> option. By default the "frig factor" (influences how far the new points are
> away from the centre of the roundabout) is set to 0.25. You can specify a
> different value as the option value: --frig-roundabouts=0.1
> 
> Large values tend to make the roundabout uglier so it would be worth
> experimenting to see what the minimum frig factor is that will stop the
> gps from reporting the wrong exit.
> 
> You can also enable frigging for an individual roundabout by tagging the OSM
> XML with the "mkgmap:frig_roundabout" tag which can either be set to a valid
> (floating point) number to specify the frig factor or just some other string
> that will make it use the default frig factor.
> 
> This patch also avoids putting in new points if the new point would be
> less than 5 or more than 100 metres from the adjacent points. This may
> stop the exception reported by Paul, but probably not.
> 
> This patch replaces the version from earlier today and is for the current
> nod branch in SVN.
> 
> As always, feedback is appreciated.
> 
> Cheers,
> 
> Mark
> 
> 
> 
> 
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> 
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