[Imports-us] Baltimore Building Outlines Import

Matthew Petroff openstreetmap at mpetroff.net
Tue May 7 05:32:14 UTC 2013

I have now reprocessed the building outlines using a method to simplify them
while preserving their topology, an important consideration due to the large
number of row houses in Baltimore. This has produced much better results than my
previous simplification methods. After simplifying the data, there were a few
hundred validation errors, instead of almost 50k with the previous method.
I have manually fixed just about all the errors. I am left with seven
"overlapping ways" warning where I can't find anything wrong with the data, all
between adjacent multipolygons.

The current outlines are here:

and as a Shapefile here:

I am working on a method to assign addresses to only one building per parcel, so
the above links are not tagged with addresses. In addition, this includes all of
the outlines, including ones that conflict with existing OSM data; these
conflicts will be separated out and reviewed after addresses have been assigned.

I have also begun to document my work on the Wiki:


On Sat, May 4, 2013 at 12:03 AM, Matthew Petroff
<openstreetmap at mpetroff.net> wrote:
> Hello,
> The City of Baltimore provides a large amount of public domain GIS data through
> their data portal [1]. Included are city wide building footprints [2], which I
> would like to import into OpenStreetMap. Other users have already started
> importing this data in a less automated way. I confirmed with the city GIS
> office that the data is indeed public domain.
> Using QGIS, I assigned approximate street addresses to each building using a
> parcel map [3] 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. 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.
> I've currently tagged the data with:
> building=yes
> addr:city=Baltimore
> addr:state=MD
> addr:country=US
> addr:inclusion=estimate
> source=Baltimore City GIS
> addr:housenumber=[Based on parcel data]
> addr:street=[Based on parcel data]
> I've uploaded the files here for feedback:
> http://db.tt/P9qh1hIm
> Thoughts, suggestions, questions?
> -Matthew Petroff
> [1] https://data.baltimorecity.gov/
> [2] https://data.baltimorecity.gov/Geographic/Building-Footprint-Shape/deus-s85f
> [3] https://data.baltimorecity.gov/Geographic/Parcels-Shape/jk3c-vrfy

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