Hi Ido, Could we have more information about how the road detector works? I gave it a quick try, and wrote a few thoughts about it after making a short comparison with the use of Dijkstra's algorithm. See http://tnorth.ch/blog/index.php?post/2011/02/04/Bing-road-detect-API-and- vectorization
Thanks, Thibault > On Fri, 2/4/11, Ido Omer <ido.o...@microsoft.com> wrote: > > From: Ido Omer <ido.o...@microsoft.com> > Subject: [OSM-talk] (magical?) road detector > To: "talk@openstreetmap.org" <talk@openstreetmap.org> > Date: Friday, February 4, 2011, 7:59 PM > > Hi Guys, > > I am a researcher at Microsoft and I am currently working on the road > detector. I joined a bit late and can’t post answers in the existing road > detector thread, but I might be able to provide some additional info > regarding the road detector. It is *FAR* from being perfect, but in our > experiments it may produce a lot of value (== save time) if you use it > correctly. When use it correctly means don’t expect too much, so here are > some practical tips: 1. > It is currently uses the two end points as example and tries to find a path > that is similar to those examples, so it is recommended to use the tool at > a zoom level that will let you make sure you click on a road and not near > a road (we will probably loosen that restriction in the future). 2. > Don’t try to challenge the detector too much, it will probably fail, > instead if you have a very complicated winding road break it into a few > sections and let it detect shorter legs (it will still save you most of > the clicks…) > 3. > One of the main features used is color, so if the road changes its color a > lot, break it again into shorter legs. 4. > We currently only compute one path (road) between the points and cannot > provide a meaningful score for that path. Defining a score is a difficult > problem (but we are open to ideas…). 5. > To speed things up, we are using a bounding box that is in many cases > smaller than the bounding box provided by the client (we take constant > margins around the bounding box defined by the two end points). This means > that if you click on the two end points of a U shaped road we might > truncate the lower part of the U and find a “shortcut “ through buildings, > fields, etc. And again you’ll need to break the query into shorter legs… > (I am currently working on speeding things up and I hope to get rid of > this limitation in a week) > 6. > The algorithm is currently ignoring junctions, but I should be able to add > them very soon (early next week) That is for road detection. The other > mode we will provide is road exploration which will enable finding all the > roads in a certain bounding box (well, you’ll probably need to click once > or twice…) I am not sure if there is an exposed version of this service (I > hope not, since so far it is really a bunch of experiments…) but we should > have it really soon (a week or two). For the road exploration we will > probably have some kind of certainty level for each road segment. > I will be very happy to hear of any complaints/requests/places where you > think the detector should work but it fails/any other feedback. > Thanks, > Ido > > > > > > -----Inline Attachment Follows----- > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
