Yes, the TIGER upload is a one-time starting point for the map. And yes, the TIGER data leaves lots to be desired. I have noticed that TIGER assigns primary to US Highways, secondary to state highways. Personally, I don't think there's that much difference, but I'm reluctant to change them. TIGER has no knowledge of county highways, which I plan to make tertiary.
The satellite imagery is good, but beware: 1. the satellite images may not be aligned correctly; you should check across the area with a GPS. 2. the satellite imagery available through Potlatch is older than, say, the imagery on Yahoo maps; this doesn't matter in places where the roads haven't changed recently, of course. I don't think we're going to see an automated imagery "havester" anytime soon. I don't know about the details of the deal with Yahoo, but I think the intent was as an aide to data collection, not a primary source. On Dec 31, 2007 4:03 PM, Shawn Rutledge <[EMAIL PROTECTED]> wrote: > It's very nice to have this data imported, despite the inaccuracies: > it saves a lot of trouble with entering metadata. > > I assumed the idea is that it's a starting point, right? The last > couple weeks I've been editing some of those ways to make them more > accurate... many intersections are not aligned with their actual > positions, nodes need to be added to make straight ways match curves, > and every street is tagged "residential" so I've been changing the > highway type to something more appropriate for the major 1-mile and > 1/2-mile streets in Phoenix, AZ. I've been using primary for streets > that are also state highways (there are just a few of those), > secondary for the 1-mile streets, and tertiary for the 1/2-mile > streets, with some exceptions when a tertiary street is actually more > important and is promoted to a secondary. Motorways were already > tagged correctly but I've been editing them to make sure there are > dual ways, one for each direction. For example this area is very > close to home and I spent a lot of time on it: > > > http://www.informationfreeway.org/?lat=33.362129805432126&lon=-111.99522509084402&zoom=14&layers=B000F000 > > I was using GPS traces with JOSM at first, but realized it's actually > more accurate to use the satellite imagery (and I don't have to plan > on driving every street eventually!), so I did a lot in Potlatch the > last couple days (and once I get started it's really hard to stop... > I've got to back off a bit now). I also hike most weekends so have > been carrying a GPS to capture hiking trails, and I do that work in > JOSM. > > So I hope my fixups will be persistent. The TIGER import was only > supposed to happen once, right? > > And I cases where there are multiple ways describing the same actual > street, I usually delete the non-TIGER one because there is less > metadata, and clean up the TIGER data to be at least as accurate as > the one I deleted. > > I was also thinking, wouldn't it be nice if there were something like > OCR for satellite images? i.e. an algorithm to pick out the streets > from the rest of the landscape. The TIGER data would provide the > metadata, and this correction of it to match the actual shapes could > be mostly automatic. That way the image recognition doesn't have to > be perfect... if the algorithm sees an edge that's not "close enough" > in position and direction to a TIGER way, just ignore it and let the > humans deal with that area of the map. > > _______________________________________________ > newbies mailing list > [email protected] > http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/newbies >
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