Thank you everyone for the suggestions. I had originally tried using QGIS's simplify function, but it simplified things far too much, even with the minimum tolerance, and I had given up on simplification. I tried ogr2ogr's simplify function due to the suggestion, and it worked much better. This reduced the file from about 3.5 million nodes to 2 million nodes.
I had originally assigned addresses using QGIS's "join attributes by location" function, set to take the attributes of the first located feature using the building outlines and the parcel map. This lead to errors due to slight misalignments of the building outlines and the parcel map, as it would often use information from adjacent parcels if there was slight overlap. I have since redone address assignments using PostGIS to assign the address of the parcel that intersects with the building's centroid. This should result in correct address information in virtually all cases, as it is quite rare for a building to be on two or more parcels. Multiple addresses on large buildings are not being handled; the only address data available from the city is the parcel map, so buildings are being assigned that address. In regards to labeling garages, it's much easier to do so. I suppose one could only label the largest building on each parcel, but that would probably lead to buildings that should be labeled not being labeled. I used ogr2osm for conversion and tagging this time around; it made things much easier. I am planning on tagging both the individual buildings and the changesets with source information. I have removed the "addr:state," "addr:country," and "addr:inclusion" tags. When run through the JOSM validator, there are no errors, but there are ~47k warning, mostly for "crossed buildings" and "building inside building," with a few "intersection between multipolygon ways," "self-intersecting ways," and "overlapping ways." From the cases I looked at, these are the result of slight overlap between adjacent row houses, and I don't think they are an issue. I have not yet decided how I will upload the data. I'll probably test a few things on the dev server first. In regards to licensing, I think the confusion results from multiple departments adding data to OpenBaltimore. I will get in contact with the city again and try to get a more formal public domain dedication for the data. Here is an updated copy of the buildings: http://db.tt/vIpWQ6OZ I left the data in one file this time after I found that JOSM still worked with the large amount of data, although it was a bit sluggish. -Matthew On Sat, May 4, 2013 at 12:03 AM, Matthew Petroff <[email protected]> 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 _______________________________________________ Imports-us mailing list [email protected] http://lists.openstreetmap.org/listinfo/imports-us
