[OSM-talk] Deleting data

Russ Nelson nelson at crynwr.com
Sat Oct 19 13:48:11 UTC 2013

Serge Wroclawski writes:
 > Though I'm not the person you're talking about, the problem with your
 > argument, in your case is that you map things in places you have not
 > been.

Some, yes, and some, no. How would you know without talking to me?

Here's a perfect example:
Do you see a railroad there on the Bing imagery? I don't.

I mapped that railbed by looking at aerial photos and old and current
public-domain maps. Then I visited it, and it was *exactly* as I had
mapped it. Well, being there I found a few improvements, but that's
the point, right? And even better, I found out that it was an official

 > I've seen imported data from you that was created before the LWG's
 > position on these things, and a lot of it is *highly* suspect.

Suspect in what sense? Copyright-infringed? Nope. I use 100% USGS data
and in many cases my own eyes. Did that data come from outside OSM?
Yes, it came from a pre-OSM database every point of which I clicked.
The shapefile is still available at http://russnelson.com/nyrr/
It's the result of decades of work, and you can observe the progress
in the changing versions.

Don't accuse me of violating copyright. Don't even GO there.

Have I done the field work to verify all of this mapping? No. Here is
my todo list: http://rutlandtrail.org/todomap.cgi
Feel free to ask me to add to it.

 > So I can imagine that someone else, encountering similar data, would
 > make a similar conclusion "This data is wrong, thus needs to be
 > removed. When I've encountered this kind of data from you, I've
 > reached out and contacted you, and you've corrected some of it.

Imagine away, but they left out the "contacted you" part.

 > As a mapper, you have mapped from third party sources and not been in
 > the place physically to confirm. But you expect other mappers to have
 > a different threshold for deleting these edit, why?

Because they are not an expert. Sorry, they're not. You have to use
multiple sources to find a railroad right-of-way. You can't just look
at a leafed-over aerial photo (as above), or an aerial photo where you
can't identify the railroad remains. Sometimes it's as subtle as a
tree-row with a few extra-tall trees (I traded the SH&E that way and
later found a US Army map that had the whole thing mapped exactly as I
had it). Sometimes it's a pile of rocks or a bit of concrete that
doesn't belong there. Sometimes it's buildings with a corner cut off,
or a wall askew. Sometimes it's a bit of pavement that's a darker
color. You go look on the old maps to confirm, and yep, it's
there. Sometimes it's just a vague shadow on a not-current but not
particularly old aerial photo.

 > I agree that we need better communication mechanisms and better
 > monitoring of edits. I do not agree that deletions should only happen
 > when someone has physically gone into the area other.

I didn't say that, and I agree with you. I said that if you haven't
been there, and the person who put it there objects, you should
presume that they know better than you. Humility, not arrogance.

--my blog is at    http://blog.russnelson.com
Crynwr supports open source software
521 Pleasant Valley Rd. | +1 315-600-8815
Potsdam, NY 13676-3213  |     Sheepdog       

More information about the talk mailing list