We are going to experiment with using OSM infrastructure to gather, consolidate, and standardize parcel data. So we need a sandbox where it’s safe to experimentally import data. I brought up an instance of the rails port in order to do this. I did this mostly following the general rails port instructions and the Ubuntu-specific instructions. Then I fussed around with the templates and content in a completely non-upstreamable fashion. Ta da. OpenParcelMap. Many integration steps remain. Like getting planet dumps and tiles in place, for example. A few higher-level issues have also come up as I’ve gone through this process.
One thing is this: I’m starting to believe that the OpenParcelMap will rely heavily on imports of government datasets. This belief has emerged from some chats on email@example.com where people point out that parcel boundaries cannot really be observed by on-the-ground mappers without special information (e.g., a legal description of the parcel), special expertise, and possibly permission to access the property. Also, much parcel data (such as boundaries and zoning) change administratively with no change on the ground at all. So the utility to this parcel data project of OSM as a crowd-sourcing platform is perhaps less compelling than its utility as a version control system for geospatial data and a distribution scheme.
Another issue that is looming on the horizon is the prospect of keeping parcel data up to date. Honestly, I haven’t given this much thought. I’m sure other OSM users have given this sort of problem much more thought than me. But that’s what this rails port is for: experimenting with these issues, trial-by-fire style.
There’s also the matter of coherency with OSM. Parcel data often comes with addresses and building info, which, unlike parcel boundaries, are currently acceptable in OSM. Should we even bother uploading address info into the OpenParcelMap? Or should this just go into OSM? This which-data-goes-where issue has come up in discussions about introducing the notion of layers in the OSM data model. I’m really not sure what to do here.
Finally, there’s the matter of licensing. One of the things I changed in the content is to make it clear that all of the data that goes into the open parcel map must be public domain. This is not a final decision. At this time we’re mulling over the pros and cons of using the ODbL, sticking with public domain, or doing something else. And by all means, if you have are reading this and have some thoughts on the matter, please comment. The only evaluation criteria I’ve come up with for this choice so fare are to maximize the likelihood that government agencies who maintain parcel data, to maximize compatibility with existing OSM data, and/or to maximize the participation from mappers interested in managing regions of parcel data. I suppose my next post will be exploring this issue in more detail.