[Imports-us] Palo Alto, CA Building Outlines import

Serge Wroclawski emacsen at gmail.com
Mon Jul 22 15:17:57 UTC 2013


On Mon, Jul 22, 2013 at 10:25 AM, the Old Topo Depot
<oldtopos at novacell.com> wrote:


> The city of Palo Alto, CA has released a set of building outlines, and I've
> created an .osm file from that data at
> https://github.com/oldtopos/PaloAltoCA

Comments on the osm file at the bottom.

> A wiki page discussing this proposal can be reviewed at
> http://wiki.openstreetmap.org/wiki/Palo_Alto,_California/Buildings_Import#Data_Transformation_Results

John,

The purpose of this list, and this group, is to work collaboratively
and also to build consensus, so I'm glad you're bringing this import
up.

One question that is looming large in my mind is the question of
timeframe, and feedback, since there is a lot of "will" language in
the wiki.

How much time will you give us for participatory feedback?

Now onto some questions.

The license for this data is "interesting"- in that it has a lot of
terms in it which I don't understand, because I suspect they have a
different meaning in legalease than they do in plain English.

Has the LWG seen this license?

> This import does NOT include comprehensive address points, which is not
> currently available as an easily imported dataset.

This question of the value of building outlines without their
corresponding addresses comes up very often.

Building traces are very high in terms of data density, but without
something like an address, they can be very noisy with little benefit.
Is there a plan to get addresses, or at least address interpolation
data, to go alone with the high density data?

> The city also as has a land use polygon dataset (among others) that I'll use
> to update existing shapes once this import has been approved.

We've discussed landuse, especially in California, and found it to be
of very low quality. There seems to be a growing consensus in this
group that landuse isn't that valuable in general. I'm still somewhat
neutral on this topic, but I'm increasingly persuaded not only by the
arguments that have been presented, but by the compelling evidence
that landuse imports have been especially bad in the US.

On the OSM file, I echo Jason's sentiments.

The overlapping buildings is really confusing to me. I don't
understand what that is- can you explain it?

As Paul Norman and others have pointed out in the past, including a
source_id on an object does not really help- so it's not generally
encouraged (and I'd argue for its removal). Source tags on objects,
too, is generally not needed, as we can get that same information from
the changeset.

My other question is regarding your conflation process and the future.

Your github contains the output file, but is it possible for you to
share how you derived at that data?

Also, I'm thinking about in a few years, if the city has a new
dataset, how it would be possible to conflate the datasets between
what is in OSM and what's in the new dataset, both adding new
building, and removing buildings which have been deleted from the new
dataset, or even buildings which were removed from OSM but still
appear in the city data?

Some of this will need to be handled by manual review, but the
question is- based on working with this data, do you have any thoughts
to share about it?

- Serge



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