Hi Cathy, once I've been to Edinburgh, came by ferry and car to explore the northern coast of Scotland. That was a nice time. Now I have a wife, a house and a child leaving not much possibility for such travel. But luckily I can do other things :-)
I think I can help you a bit. 1st I think that these double nodes are errors. Done by whatever version of whatever program. I think you can not prevent all errors. I think the API should reject those ways. However, now they are there. JOSM now has a good validator plugin. But it's a plugin, has to be installed deliberately and has not been there all the time. I will write a check program for these which we can use to identify those ways. Not a big deal. Should be done today or tomorrow. But then they will only be identified, not corrected. I just know about problems in routing, I don't actually "route" myself. I am the "checker". :-) One other thing. I think the OSM data/graph should be simplified to save ressources when routing. I could imagine a simplifier eliminating those nodes and those that are not the end of a road and don't connect to anything else. Of course the weight/length of the original path should be maintained. Cheers Gerhard gary68 --- Scott, Cathy <[email protected]> schrieb am So, 4.1.2009: > Von: Scott, Cathy <[email protected]> > Betreff: [Routing] Errors in map data that affect correct routing - and what > to do about it... > An: "[email protected]" <[email protected]> > Datum: Sonntag, 4. Januar 2009, 22:56 > Gerhard, > Thank you for posting this . I'm just away to look at > it. > I am studying for a PhD that is based on routing > algorithms. At present I have a MYSQL copy of the > Openstreetmap data for Edinburgh that I am using for this. > I certainly have issues with the accuracy of this data that > is > causing issues with routing. Ways that are not connected to > an others are certainly an issue. I was just about to come > onto the forum to post about it when I saw your post... > > One of the other issues that I have are Ways that appear to > have extra nodes on them that I do not understand why they > are there. I'm assuming that they are errors but I > wanted to double check first... > > For example there is a road called Charles Street in > Edinburgh way id =7972092. This way has 4 distinct nodes but > the last one is repeated so that a routing algorithm moving > along the street would move from node id= 287241490 to node > id=287241490. > I'm assuming that the above example is an error. There > seems to be plenty of them too. In the Edinburgh area I have > identified about 100. Some of them are completely > unnecessary Ways. For example Blacket Place is represented > by two ways. the first id=27992340 appears to be valid. The > other way id=4048677 consists of one node(id=307349548) 12 > times! > > Of course I could code any routing algorithm to ignore > these 'null' moves but I was wondering;- > a) How do these errors get there? Can validation checks be > added when ways are created/updated? > > b) Have you found an issue with these errors or are you > just coding to ignore them? > > Thanks, > Cathy > ________________________________________ > From: [email protected] > [[email protected]] On Behalf Of > [email protected] > [[email protected]] > Sent: 31 December 2008 12:00 > To: [email protected] > Subject: Routing Digest, Vol 16, Issue 9 > > Send Routing mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.openstreetmap.org/listinfo/routing > or, via email, send a message with subject or body > 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more > specific > than "Re: Contents of Routing digest..." > > > Today's Topics: > > 1. Errors in map data that affect correct routing - and > what to > do about it... (GS) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 31 Dec 2008 10:10:51 +0000 (GMT) > From: GS <[email protected]> > Subject: [Routing] Errors in map data that affect correct > routing - > and what to do about it... > To: [email protected] > Message-ID: > <[email protected]> > Content-Type: text/plain; charset=utf-8 > > hi, > > from time to time people encounter errors in routes or > destinations can't be reached. there are a lot of > reasons for this. and a lot of reasons can be found in the > output of my check programs. > > so if you no longer want to do "trial and error" > and want to correct the map data proactively have a look at > the programs and their outputs. > > waycheck looks for unconnected endpoints of ways and > crossings of ways on the same layer where the ways don't > share a common node. > http://wiki.openstreetmap.org/wiki/WayCheck > > checkconn does the above mentioned check, but faster and > with less memory. > > checkcross does the above mentioned check, but faster and > with less memory. > > checktouch checks for endpoints of ways that nearly touch > another way. so presumably these ways should be connected. > > motorwaycheck checks for invalid motorways (invalid oneway > tags and possibly wrong directions of ways). > http://wiki.openstreetmap.org/wiki/MotorwayCheck > > lots of reports can be found here: > http://wiki.openstreetmap.org/wiki/DE:WayCheck > > all programs can also be found on my wiki page: > http://wiki.openstreetmap.org/wiki/User:Gary68 > > generally there is a wiki page for quality assurance here: > http://wiki.openstreetmap.org/wiki/Quality_Assurance > > > cheers > > gary68 > gerhard > > > > > > > > > > > ------------------------------ > > _______________________________________________ > Routing mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/routing > > > End of Routing Digest, Vol 16, Issue 9 > ************************************** > > > Napier University is the best modern university in > Scotland* and number one in Scotland for graduate > employability** > (*Guardian University Guide 2009) > (**HESA 2008) > > This message is intended for the addressee(s) only and > should not be read, copied or disclosed to anyone else > outwith the University without the permission of the sender. > It is your responsibility to ensure that this message and > any attachments are scanned for viruses or other defects. > Napier University does not accept liability for any loss or > damage which may result from this email or any attachment, > or for errors or omissions arising after it was sent. 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