[Imports-us] Leveraging MassGIS L3 Parcel files for assisting in manual address merging

Lars Ahlzen lars at ahlzen.com
Sun May 24 01:01:51 UTC 2015

Hi Frederick!

First of all, kudos for working on much needed address data in OSM!

At a cursory glance, it looks pretty good from a technical standpoint. I do
think that even if it's done semi-manually and fractions of a town at a
time, it's still an import and should probably follow the import
guidelines. That's a good checklist for making sure you get things right
anyway (which is surprisingly hard!).

We do have some locals here in MA with lots of experience of imports, and
who are also familiar with that particular dataset, that may be able to
provide some additional feedback as well.

That said, I would like to take a step back to make sure importing
addresses from the MassGIS L3 Parcel data is our best option. While I
frequently use it for determining hard-to-survey boundaries, I have some
questions about its usefulness as an address source:

As far as I know there are still towns/cities in MA, such as the city of
Boston, for which L3 data is not (yet) available. I realize you're not
necessarily proposing an import of the whole state, so it may not matter in
your case. However, scattered address data is less useful than a state-wide
import (though, I suppose, better than nothing).

The L3 data has, as far as I know, a single address or address range per
land parcel. I'm sure that's fine in most places, but I imagine it can lead
to some tricky cases in denser areas. For example, I could find several
examples of one parcel with multiple buildings and a range of house
numbers. In that case, how would you do the mapping from house numbers to
buildings? What about a parcel with one house number and multiple buildings?

Also, there's a rumor that MassGIS is going to release proper address data
with a compatible license. In fact, that is probably the main reason that
we've held off on any address imports in MA. It still hasn't happened, and
I'm not sure if it ever will, but it may be worth looking into before doing
this on a larger scale.

- Lars

On Sat, May 23, 2015 at 6:31 PM, Frederick Hunter <fhunterz at verizon.net>

> Hi All,
> I am still relatively new to OSM and have come up with what I think is a
> more efficient way of adding address data to buildings using JOSM.
> So far I have added a number of addresses to Maynard, MA and began
> working on Concord, MA using the JOSM L3 Parcel background layer. This
> has taken a very long time, and I am hoping to get some buy in for this
> more efficient way of importing address data to OSM.
> I created a quick overview of my idea and proof of concept on my blog
> https://www.openstreetmap.org/user/xunilOS/diary/35076.
> High level overview of what I would like to do:
> 1. Create .osm xml file with a towns addresses using a script and L3
> Parcel data
> 2. Temporarily import address nodes into JOSM
> 3. Download a section of the town for editing
> 4. Merge the address nodes with buildings, verifying addresses are in
> line with L3 Parcel background layer
> 5. Delete all the address nodes based on a unique tag I can search by
> 6. Upload changes to OSM
> 7. Using OSM Inspector check for road name mismatches or other errors.
> Before using this method, I would like to gather some thoughts or things
> I may want to do differently from the folks on this thread.
> A few questions I specifically have.
> 1. Can I do this?
>    - I would imagine this is no different than using the MassGIS L3
> Parcel data layer in JOSM as the data is coming from the same source and
> the wiki page on massGIS states it can be used as long as it is
> sourced.
> 2. Does this qualify as a bulk import and need to go through the a
> complete import review / community buy in ect.. as stated on
> https://wiki.openstreetmap.org/wiki/Import/Guidelines.
>    - The way I see it, the data is coming from the same source which
> has already been approved. Also, the merging of address data is still a
> manual step as I don't want to upload addresses as single nodes, but add
> them to buildings. This would allow me to verify the address numbers are
> in line with the L3 parcel data layer in JOSM.
> Many thanks in advance for your thoughts,
> Frederick
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Lars Ahlzen
lars at ahlzen.com
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