On Wed, Mar 28, 2012 at 11:00 AM, Martijn van Exel <[email protected]> wrote: > Hi all, > > On Wed, Mar 28, 2012 at 6:48 AM, Ian Dees <[email protected]> wrote: >> >> On Wed, Mar 28, 2012 at 5:47 AM, Josh Doe <[email protected]> wrote: >>> >>> Hardest part will then be scaling this up to all 3140 counties. >> >> I'd love to hear from anyone else that has ideas. >> > > As for scaling, it may be preferable to process counties on request, it is a > pretty expensive operation especially when you get into the details and > start realizing all the subqueries you'll need to get it right. The added > advantage is that it is easier to keep track of the counties that are > already looked at, at the expense of some overhead coding.
We'd certainly start there, and see how it goes. > Queries to find missing roads entirely based on intersection are not likely > to be very successful for two reasons: 1) TIGER spatial accuracy is bad > enough to generate a lot of false positives and 2) a buffered OSM road will > likely intersect more than one TIGER road, even if the actual road does not > exist in JOSM. True, but this will vary by region. My area (Fairfax County, VA) has very high spatial accuracy since it comes from the local high quality county database. > What you could do is buffer all OSM roads and filter those TIGER roads that > are more than x % outside of the resulting polygon. Those may be candidates > for missing roads. Another interesting case for a microtasking platform by > the way, to have people who are not necessarily experienced OSM editors > identify the valid missing roads from the resulting dataset. Yes, we'd definitely need to do use a %, or at least shorten each way before buffering so as not to get all roads at intersections. -Josh _______________________________________________ Talk-us mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-us
