[Imports-us] Baltimore Building Outlines Import

Paul Norman penorman at mac.com
Sat May 4 23:23:27 UTC 2013


Thanks for the proposal, I have a few comments

> From: Matthew Petroff [mailto:openstreetmap at mpetroff.net]
> Sent: Friday, May 03, 2013 9:03 PM
> Subject: [Imports-us] Baltimore Building Outlines Import
> 
> Using QGIS, I assigned approximate street addresses to each building
> using a parcel map [3] 

Could you provide details on the method used for assigning addresses?

> and used the field calculator to clean up the
> labels and remove abbreviations. In addition, I removed all data that
> intersected with existing buildings to preserve existing work. I then
> separated the data into smaller chunks and converted the Shapefiles to
> OSM with Merkaartor. After simplifying Merkaartor's output using
> osmconvert's "--drop-author" switch, I tagged the data with sed, before
> finally using JOSM to remove duplicate vertices and empty tags. 

Although your technique works, both ogr2osm and shp-2-osm.jar will convert
shapefiles to .osm and convert tags with fewer steps than what you've done.
If yours works that's okay, but it does involve a lot of steps.

> My only
> qualm with the data is that some buildings have more nodes than they
> need, but I'm not sure what can be done about it besides manually
> reviewing and simplifying all 200k+ outlines.

The data definitely needs to be simplified. As a random example, look at
3610 Glen Avenue, it uses 49 nodes for a rectangle. ogr2ogr, QGIS or JOSM
should be able to simplify these for you. A 25cm threshold simplify in JOSM
brought down the number of nodes in 0ed.osm from 500k to 215k (27k ways).

> I've currently tagged the data with:
> building=yes
> addr:city=Baltimore

> addr:state=MD
> addr:country=US

Current wisdom is that it's not worth including addr:state and addr:country.

> addr:inclusion=estimate

I've looked at the docs for addr:inclusion=estimate, and it doesn't look
like this fits what's documented.

> source=Baltimore City GIS
> addr:housenumber=[Based on parcel data]
> addr:street=[Based on parcel data]

The address assigning logic looks reasonable in many cases, but I'm seeing
two types of recurring errors that are occurring

The first is tagging both the house and garage with the address.

The second is something weird going on which might be matching wrong parcels
to buildings at 3610 Glen Avenue. I've put up a screenshot at
http://maps.paulnorman.ca/imports/review/baltimore/oddnumbers.png and can
take a look when I know more about the parcel to building logic.




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