[Imports] TIGER realignment import

Paul Norman penorman at mac.com
Tue Aug 6 07:47:40 UTC 2013

> From: Eric Fischer [mailto:enf at pobox.com] 
> Sent: Monday, August 05, 2013 3:26 PM
> To: imports at openstreetmap.org
> Subject: [Imports] TIGER realignment import
> Hi everybody. It's probably time for me to stop just talking about 
> importing the TIGER realignment and actually do something. 

It's good to see some progress made

> My questions are: 
> 1. Is there still general agreement that it is a good idea to import 
> realignments for places that have been neglected in OSM?

Looking at the file sizes, I'm struck by how different they are. The 
first two that me and Serge looked at were ~100K, but some are over 100MB.

It would be useful to know which counties have so few changes it would be 
easier to manually review. Maybe a count of changed ways? The first one I 
reviewed had 14 ways in it.

> 2. Is it OK for me to go ahead and start submitting some of these? 
> (I'll make an import account.)

It would be premature, since you proposed this on Monday and .osc files are 
very tricky to review when they involve geometry changes.

> 3. Is there a test server where I should try submitting them first?

To test this properly what you need to do is get some sample data into a 
dev server, either master.apis.dev.openstreetmap.org, or one that you run.

For the former you'd have to download some data, convert it into an 
uploadable file and upload it to the test server. Running one yourself 
might be easier.

> 4. Is there an upload script I should be using instead of doing it 
> from JOSM?

Serge might have a script, but if you're using something non-standard then 
you definately need to test it on a test server.

> 5. Do the files look sensible now to people who have more experience 
> with .osc files?

The files seem valid.

Although not wrong in any way, I was surprised that modified nodes are 
in as <node ...>\r\n\t\t</node>. What XML library are you using to create 
the .osc files?

Now, for some preliminary comments and questions

53061-0000.osc modifies way 40495680 which isn't a road at all. I'm not sure

I see a number of forestry roads in 53061-0000 being modified with no 
apparent changes in geometry. An example is way 6126562 (National Forest 
Development Road 020). It has node 50690471 at 48.117638, -121.766767 in 
it. The .osc file creates a new node at 48.117638, -121.766768 which is 
a move of about 10 mercator cm. If this was a once-off I'd not mention 
it, but most of the changes in 53061-0000 are like this. 

It seems to of missed changes present in the TIGER overlay near 
48.284822, -121.83297 in way 6118160 but it modified other parts of the 

Way 6118167 is self-intersecting. It also appears that the version in 
OSM hasn't been edited at all, so there's some algorithm failure. As it 
happens, it also doesn't correspond to anything at all on the ground. 

Way 6137727 becomes highly distorted, again with no apparent cause. 

In 56025-0000.osc node 157668125 is modified in the .osc file but no 
changes are actually made to it. It is not moved at all. This seems to 
be fairly common and makes it hard to review the changes because there 
are so many "false positives" when looking for changes. 

In the same file node 157626325 is modified with no movement and neither 
of its parent ways are actually present in the file. 

Overall I'd say this is actually pretty good for a first review. .oscs 
are hard to generate, and hard to do QA on. 

More information about the Imports mailing list