On Thu, Mar 26, 2009 at 1:00 PM, William Lachance <[email protected]> wrote:
> I've been following the discussions about the geobase import with > interest. There seems to be some concern about how to correlate the > existing OSM data with the Geobase dataset. In particular, how do we get > the superior positioning and connectivity of geobase without blowing > away all the great work people have done tagging their manually inputted > ways? I keep seeing people talk about the superior positional accuracy of the GeoBase data. From the sections that I have interacted with, I would find it hard to support this statement. The position accuracy of the GeoBase data that I have dealt with is very easily recognized as much less than the OSM data. However, the sheer volume of GeoBase data makes the database of interest. I have higher accuracy, or at least better representational data in the OSM database in areas where I have been working, but I am still interested in blowing away all of the data that I have entered in favour of importing the full GeoBase data set. From there I will once again go over the GeoBase data, and fill in the extra data required to bring the GeoBase data up to the OSM data representation level. This is worthwhile in my opinion due to the ability to have large amounts of lesser quality data in areas where there is currently no data at all. > One alternative which I haven't heard mentioned is the possibility of > _merging_ the two datasets. That's what is happening now, using a script that watches for existing roads, and skipping them. The issue is stitching the newly imported roads to existing roads. The problem appears to me to be the fact that the existing ways will need to have nodes added to them for the imported ways to link to. The software being used right now does not do that, but rather just stops the import at the next closest node on the imported way. There will need to be some type of decision making process happen in the import scripts that either a) finds a node on the existing OSM way that is within a specified distance from where the imported node should be, or b) create a new node on the existing way, and connect the imported way to the newly created node on the existing OSM way. This would solve the issue of having the two road databases being separate, but it would still require manual intervention to fix the inevitable problems. If you look at the example from Camrose, you will see that some GeoBase roads stop short of the OSM way, while others cross the OSM way. If a new node was added and connected to the node that crosses the OSM, it will look like there's a mini off ramp or something. James VE6SRV _______________________________________________ Talk-ca mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-ca
