On Thu, Aug 05, 2010 at 01:38:36PM -0500, Ian Dees wrote:
> I think the NHD "import" is a good example of a well-intentioned importer > (me) gone wrong. I had initially planned to import the whole darn thing in > one swoop, but various technical and life challenges came up before I could > get it going. While I was working on those issues, people started importing > it themselves (sometimes marking so on the wiki, sometimes not). Now that > there are some areas imported, the import of the whole dataset becomes > infinitely harder because we have to match existing data with new OSM-ified > data. And I'll add my own mea-culpa. I created some wiki pages/features to help partition and coordinate NHD import efforts, and then also found that I didn't have the time to follow up. I would agree that the partial imports will have increased the difficulty of a large-scale bulk import, but we already had hydrographic features from TIGER, did we not. And hand-drawn features from aerial traces and actual boots-on-the-ground mapping. Conflation in general is a tough problem, I gather. There are tools, algorithms and heuristics in the GIS world but the OSM data model makes translation between the two models somewhat difficult. For example, something that looks very interesting which I plan to examine is the Java Conflation Suite [1], which looks like it could be used over relatively small areas (probably about the size of the API limit... 0.25 degrees square?). But as a component of the JUMP[2] platform, it operates only on Shapefiles and GML out of the box. (If we could get some Java expertise I think it would be very worthwhile working with the JUMP team to create an OSM driver.) At any rate, while I think we could mitigate a number of problems given some development effort, I also agree that we might want to spend more time thinking about why we want to make the imports--and perhaps publically debate, if only in talking to yourself on the project wiki page, the pros and cons of a particular import. [1] http://www.vividsolutions.com/JCS/ [2] http://www.vividsolutions.com/jump/ _______________________________________________ Talk-us mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-us
