[Talk-us] [Imports] Fresno castradal imports

Paul Norman penorman at mac.com
Fri Apr 27 10:13:06 BST 2012


> From: Toby Murray [mailto:toby.murray at gmail.com]
> Subject: Re: [Imports] [Talk-us] Fresno castradal imports
> 
> On Thu, Apr 26, 2012 at 9:39 AM, Martijn van Exel <m at rtijn.org> wrote:
> > Hi,
> >
> > On Thu, Apr 26, 2012 at 12:54 AM, Paul Norman <penorman at mac.com>
> wrote:
> >>
> >> I happened across an import of Fresno castradal data from mid-2010 in
> >> the Fresno area.
> >> http://www.openstreetmap.org/?lat=36.77&lon=-119.81&zoom=15
> >> is
> >> the general area but I haven't fully explored the extents. For a view
> >> of the data, see http://maps.paulnorman.ca/imports/review/fresno.png
> >>
> > A few observations:
> >>
> >> 1. It is castradal data. The consensus is against dumping castradal
> >> data into OSM.
> >
> >
> > I am not aware of such a consensus - consensus among who? Is it
> documented?
> > I would expect such a consensus to appear in the Import Guidelines but
> > it doesn't.
> > Or do you mean there's a consensus against dumping data into OSM in
> general?
> > If by 'dumping' you mean 'importing without consulting the community
> > and without giving proper thought to attribute mapping and
> > generalization / normalization of geometries' then yes, I'd say
> > there's a consensus against doing that. I don't see why we would not
> > cherry-pick useful and good cadastral data for import into OSM,
> > however. It may be our only source of things like building outlines
> > (are those generally in cadastral data in the
> > US?) or address data in many parts.
> >
> > I don't mean to be nitpicking here, I just want to clarify what this
> > consensus actually is so people looking for guidance on importing in
> > the future can be more fully informed.
> >
> > [...]
> >>
> >> 8. There are duplicate nodes where data was imported on top of other
> data.
> >> For example, http://www.openstreetmap.org/browse/node/768314177
> >> http://www.openstreetmap.org/browse/node/767799968
> >> http://www.openstreetmap.org/browse/node/767770150
> >>
> >> With all of these problems I cannot think of any ways to fix the
> >> problems short of reverting the import. The tagging problems could be
> >> fixed by a script but the inherent problems of castradal data cannot
> >> be fixed without essentially deleting most of the import anyways.
> >
> >
> > Are these problems inherent of cadastral data in general, of this
> > dataset in particular, or of the way this import was conducted?
> >>
> >>
> >> I propose to delete unmodified objects from this import. I will
> >> attempt to preserve areas like schools and fix them if possible. It
> >> should be possible to keep most of them but I won't be able to be
> >> sure until I get into the removal.
> >
> >
> >  The list of issues is long enough and the issues serious enough to
> > warrant a revert.
> > What I'm missing from this list is the issue I consider to be the most
> > serious, which is that this user apparently has not consulted with
> > anyone in the community about this import. Or has he/she?
> 
> 
> I think the area where there is fairly good consensus is that mass
> imports of plot boundaries is not welcome in OSM. There was an attempt
> last year at doing this in Arkansas that ended horribly with a blocked
> account and a couple hundred thousand empty nodes.

There was also the more recent proposed import of Spanish cadastre data.

I've made use of local lots information occasionally but there I'm importing
a single object at a time, generally for the name of a school.

> In this case we have another instance of someone not considering the
> consequences of their import on the OSM community. Even if the data is
> good and valid (which doesn't seem to be a proven point in this case) if
> current tools are not able to deal with it, perhaps the import should
> wait and effort put into improving tools first.

There is a lot more awareness of what makes a bad import now than there used
to be.




More information about the Talk-us mailing list