From: Toby Murray [mailto:toby.mur...@gmail.com]
Subject: Re: [Imports] [Talk-us] Fresno castradal imports
On Thu, Apr 26, 2012 at 9:39 AM, Martijn van Exel m...@rtijn.org wrote:
Hi,
On Thu, Apr 26, 2012 at 12:54 AM, Paul Norman penor...@mac.com
wrote:
I happened across an import of Fresno castradal data from mid-2010 in
the Fresno area.
http://www.openstreetmap.org/?lat=36.77lon=-119.81zoom=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.
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