MassGIS Buildings Import

MassGIS Building Import 2013

On Dec, 2012 MassGIS released a high quality data layer for all buildings in the US state of MA. Previously MassGIS only had buildings for Boston and its nearby suburbs. The import was completed in April 2013.

Status Tracking

A google docs spreadsheet is being used to track progress on each town.

Import Check List

Source Data License

All MassGIS data is in the public domain. See MassGIS page, and talk-us archives for detailed discussion. A previous (incomplete) version of this data that covers the Boston area has already been imported.

From the MA Secretary of state Office Frequently Asked Questions, first question is

What records are public?

Every document, paper, record, map, photograph, etc., as defined by law, that is made or received by a government entity or employee is presumed to be a public record

From the MA Secretary of state Duplication Services, last section.

Records created by Massachusetts government are not copyrighted and are available for public use. Copyright for materials submitted to state agencies may be held by the person or organization that created the document. Patrons are responsible for clearing copyright on such materials. For more information on copyright law, please see the U.S. Copyright Office's web page at lcweb.loc.gov/copyright.

Scripts And Data

The final scripts to do the conversion and the uploading are linked.

Who Is Doing This

So far OSM users ingalls, OceanVortex, gdt, cspanring and jremillard are working on the import.

Simplification

The data has already been simplified by the PostGIS ST_SimplifyPreserveTopology function to 0.20 meters. When importing the OSM files, please don't further simplify them in JOSM.

Merging Existing Structures

The ZIP'ed OSM files have a OSM containing overlapping buildings. After this missing files are added we can do a separate project to merge over any hand drawn buildings from bing, using these files. For now, this is not part of this import project. We will be working on this next as a separate project.

Schema

The OSM files that are in the ZIP file will only be tagged with building=yes.

The MassGIS building STRUCT_ID will not be included. First, MassGIS made no attempt at preserving the STRUCT_ID when they updated the data set to include the entire state. The MassGIS STRUCT_ID, is based on X,Y centroid, when they updated the building locations, all of the ids changed. Second, No actual scenario came up in the discussion on why somebody might want to link the OSM structure back to the MassGIS data. In fact, nobody could come up with a case where previous imports that did include the original id turned out to be useful to somebody. Thirdly, if somebody really, really does need to link the OSM building to the MassGIS source layer, they can always link them them based on the building centriods of the two sets, and to get even more precision, rolling the change sets back to the import time and doing a more exact match will always be possible. Basically, the STRUCT_ID is redundant with the actual building geometry. Lastly, including the STRUCT_ID is not free. It will be confusing to future mappers. What to do with the STRUCT_ID, when a building is moved, deleted, or copied/ pasted? The wiki will not have this tag documented, it will not be clear what it is for. If even one fix is not made because of confusion over the STRUCT_ID tag, we will have lowered the final quality of the map for no apparent benefit.

Credit + source tag

Credit to MassGIS will be included in all changeset comments. It will read as follows Building Structures (2-D, from 2011-2012 Ortho Imagery) - Office of Geographic Information (MassGIS), Commonwealth of Massachusetts, Information Technology Division. No source tag will be used on the buildings themselves. See talk-us archive for a discussion. By including the credit in the change comment, it does not need to be managed by future mappers who will be correcting/improving on the data. For the people that want to know where specific data came from, the change history on the way will have all the needed information.