[Talk-GB] UK address project update

[Rob Nickerson]

Hi all,

I wrote in September (see [1]) about an address project that OSM UK has
kicked off. At the time I noted that one of the questions we needed to
answer was which datasets we should use to get a set of "potential address
locations" that will then be shown to contributors to help them collect the
address information. In short there are two options:

A. Open UPRN data
B. Using Cadastral (Land Registry) INSPIRE parcels to split generalised
buildings from Ordnance Survey open data, and then taking the centroid of
the split building.

I am pleased to be able to share a map (
https://osm-uk-addresses.russss.dev/ ) showing both of these approaches.

The map shows:

   - UPRN points (Green dots)
   - LR Polygons (Blue areas)
   - Ordnance Survey split generalised buildings falling within a LR
   polygon (light brown areas)
   - The addressable locations from the LR Polygons & OS Buildings approach
   (Red dots)
   - The underlying OpenStreetMap map. Note that this means you might see
   two buildings in some locations: those from OS and those in OSM (grey areas)

Firstly, please note that the red dots for Scotland are currently missing.
Scotland's cadastral parties are published by ROS and will be added to our
process early next week.

Secondly, having reviewed a few areas for the Green and Red dots, we
decided that the Red dots (LR Polygons & OS Buildings approach) gives a
better set of addressable locations.I use the word "better" very much in a
relative way. Neither approach is perfect but our view is that the red
points are a little bit closer to what we want. They have fewer false
positives which likely matters more. We're keen to get your view - do you
agree? disagree?

Finally, where the red points fall short are in dense city centres and
areas with a high concentration of council houses. This is because of a
lack of cadastral parcels in these areas (e.g. one large cadastral parcel
for the whole area rather than individual cadastral parcels for each home
or business unit). We are keen to get your ideas as to how to work around
this. So far our ideas are:

   1. Identify these locations and direct experienced OSMers to them
   (leaving the easy places for the new mappers we hope to attract) to add the
   address by ground survey.
   2. Or same as 1 but instead of the experienced OSMer having to do a
   ground survey (as might not live locally) allow them to "pull" the green
   dots through into the final user interface so that local people new to OSM
   can collect the address. This could be done by adding these to OSM; that is
   adding points to OSM that just have a UPRN or similar tag at first so that
   they can be made available in the map editor we are working on.

Feedback and alternate ideas welcomed. I am particularly keen to know if
you support idea 2 as typically we have avoided this in the past. For
example we did not add the postcode centroids to OSM. This time we can add
an addressable location with a UPRN, city, postcode and/or street name. The
final details (house name / number) would then need adding via the
crowdsource project.

I hope this all made sense. If not, I'm happy to answer questions or
arrange a virtual meeting.

[1]
https://lists.openstreetmap.org/pipermail/talk-gb/2021-September/027669.html

Thank you,
*Rob*
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