[Imports] NYC building + address import - to merge or not to merge?

[Alex Barth]

(This is BCC to tagging at osm.org, conversation to happen on
imports at openstreetmap.org.)

At the NYC building and address import we're facing the following question:

**In cases where there is one address point per building, should we merge
the address information onto the building polygon and toss the address
point?**

Originally the answer was: yes.

Now there's reason to revisit this decision: the data steward (Colin Reilly
from NYC GIS) told me that NYC GIS took great care to place addresses at
about where the entrance of the building sits.

This makes me think that there's value in not tossing the address location
information but keep it in all cases, even if there is only one address per
building.

Here is a comparison of the two options. I'd like to discuss and decide at
tonight's imports hangout.

## Option 1: Merge addresses into buildings where possible

In cases where there is one address point within a building polygon, we
take address attributes, assign it to the building polygon and toss the
address point.

Pros:

a) This is how a lot of buildings are done in OSM
b) Not regarding standing practice, merging addresses into buildings is an
exception from the generally applicable method of doing separate address
points.

Cons:

a) we lose data
b) makes it harder for NYC GIS to leverage OSM

## Option 2: Always keep address points separate

In this case we never merge addresses to building polygons, instead always
keep them as separate entities.

Pros:

a) this is the NYC GIS way, making it nicer for GIS folks to use OSM
b) this is the generally applicable method. No matter whether we have one
or multiple addresses you can expect to find a separate node carrying
address information.
c) retains useful information

Cons:

a) Diverges (but does not violate [1]) common OSM practice

Note: it has been suggested to use the address location information to tag
an entrance. Unfortunately the data is not consistent enough to do this.

## Recommendation

I'd really like to hear people's inputs here. Right now I'm leaning towards
Option 2 as it

- retains valuable information
- does not violate OSM practice

## Status quo

Note right now we've imported data in both formats :p I'm not worried about
this and I'll commit to make sure in the end we're consistent. Right now
the import is paused because of this open question.

Ref: https://github.com/osmlab/nycbuildings/issues/15

[1] http://wiki.openstreetmap.org/wiki/Addresses#How_to_map_addresses
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