[mkgmap-dev] [Patch v2] improve roundabout checks

Fri Aug 5 08:22:20 BST 2016

HI Gerd, the rationale behind choosing car in determining whether a way is
an exit was that I was expecting most people when counting exits would only
include exits that are normal roads. If we include cycleways in the test, we
run the danger of false positives where a cycleway runs alongside a road and
ends at the roundabout. I don't think it is possible to get an absolutely
perfect solution. For me, Incorrect exit hints is the prime target - though
it is not clear what we should do if the optimum layout for Garmin does not
follow OSM rules. It is perhaps questionable what should happen when a
cycleway meets a roundabout, so it seems more reasonable to not flag these
up. We could count ways with cycling access but no car access separately and
flag a slightly different warning to distinguish them. Or we could count
ways with no car access but  access to other vehicles or cycles. My prime
target would be to separate those that can be easily corrected from those
that are questionable, so I can attempt to reduce the former to zero without
having to evaluate all the questionable ones. 

Regards,

Mike

From: Gerd Petermann [mailto:GPetermann_muenchen at hotmail.com] 
Sent: 05 August 2016 05:53
To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] [Patch v2] improve roundabout checks

Hi Mike,

as a cyclist I wonder why you treat cars that special. From the previous
post I thought that we

may ignore pedestrian-only ways. 

Besides that some style authors use "car routing" to distinguish between
racing bikes and 

normal bikes. Not sure if that can cause problems here. 

I am unsure if we want to flag ways which are wrong reg. OSM rules or if we
try to find

roundabouts were the Garmin algo will produce false exit hints.

Gerd

  _____  

Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk
<mailto:mkgmap-dev-bounces at lists.mkgmap.org.uk> > im Auftrag von Mike
Baggaley <mike at tvage.co.uk <mailto:mike at tvage.co.uk> >
Gesendet: Donnerstag, 4. August 2016 23:40:38
An: mkgmap-dev at lists.mkgmap.org.uk <mailto:mkgmap-dev at lists.mkgmap.org.uk> 
Betreff: Re: [mkgmap-dev] [Patch v2] improve roundabout checks 

HI Gerd, that looks like a good start. The attached patch improves on it
slightly by ignoring highways that do not have access for cars.

Regards,

Mike

From: Gerd Petermann [mailto:GPetermann_muenchen at hotmail.com] 
Sent: 03 August 2016 14:40
To: mkgmap-dev at lists.mkgmap.org.uk <mailto:mkgmap-dev at lists.mkgmap.org.uk> 
Subject: [mkgmap-dev] [Patch v1] improve roundabout checks

Hi all,

attached is a patch for the roundabout checks. It adds a test that will warn
when 

a node on a roundabout is connected to more than one routable way 

(ways which are not accessable are not counted, e.g. highway=construction
with the default style)

The check is only performed when option

--check-roundabouts is used, you have  to enable logging to see the result.
The check is implemented in class RouteNode, so a config line in
logging.properties might be

uk.me.parabola.imgfmt.app.net.RouteNode.level=WARN 

A binary based on r3688 is here:

http://files.mkgmap.org.uk/download/306/mkgmap.jar

Note that this check is very basic, it doesn't ignore when the road is going
straight through the roundabout

or when it builds a tagent. If you think that this produces too many false
warning I may add 

code for this. 

Gerd

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