[OSM-newbies] editing TIGER data

[John Wolter]

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 <shawn.t.rutledge at gmail.com> 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.
>
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