OGC and real property and mortgage records standards

Mapping property ownership is one of the oldest uses of geospatial technology in human history, going back at least 4,500 years to Babylonian times. And today, every government invests significant resources in managing property ownership records with GIS. So it’s surprising that no standard real property data model and no standard way of assigning unique property identifiers have been devised to support the buying, selling, and mortgage-backed financing of real property.

Late last year, OGC was asked to help address this shortcoming, working with MISMO, (Mortage Industry Standards and Maintenance Organization) and ECCMA (Electronic Commerce Code Management Association) to leverage geospatial standards to do two things:

1.     Augment MISMO’s residential property XML data model with a section to describe the spatial characteristics of a land parcel and/or its buildings

2.     Use this spatial description to create a “global, natural” unique ID for the property, called a PNIU (property natural identifier-unit). The ID must be natural in that it can be derived from the characteristics of the property, without relying on a third party such as a central property registry, to mint and manage IDs. And it must be global in that it does not rely on the property ID systems of any particular county, province, country or other jurisdiction.

parcels in GIS and Google Earth

The same parcel boundary shown in a desktop GIS (left) and in Google Earth (right)

To solve problem 1, encoding the property in XML, OGC offers the options of GML and KML. These property records will be crossing the desks of bankers, regulators, and the like, and as this community rarely has sophisticated geospatial  tools, and thus KML was prefered as it could be easily mapped with consumer grade applications such as Google Maps and Earth. OGC’s KML is now implemented by a wide range of non-Google apps, many of which can be found on our web site.  As simple as KML is, we needed to make it even simpler, so OGC helped develop a subset of KML for this project, which is specified in ECCMA/DSTU 1-3, Geographic information — Description and identification of real property location — Part 3: Lot.


Graphic of the subset of KML for real property. See the ECCMA draft spec for the formal XML schema.

Problem 2 is more complicated. ECCMA has drafted an approach to deriving a PNIU which takes the elevation and geographic coordinates of the front door and uses an encoding technique to shorten the coordinate expression to 16 ASCII characters. This is specified in ECCMA/DSTU 1-4, Geographic information — Description and identification of real property location — Part 4: Unit space.

The only problem with this approach to the natural ID problem is that it’s unlikely that two different people – even surveyors – will come up with the exact same elevation and coordinates for the front door. So this works when everyone starts with the same base data, but someone going back a few years later to survey the property will come up with a different PNIU. I’d prefer an approach to defining the geography that is coarse enough that any two people will come up with the same result, but detailed enough that no two properties can possibly have the same PNIU. We continue to pursue an approach from this line of thought and I’ll discuss progress in future posts.

In a post-banking crisis era, these improvements in real property information flow are critical. As Edward J. DeMarco, the acting director of the US Federal Housing Finance Agency, said in testimony to Congress earlier this year, “Working through the process with a broad-based coalition of industry participants in MISMO should serve as a model for future efforts as we seek to rebuild the foundation of the mortgage market. In the end the benefits are immense. Developing standard terms, definitions, and industry standard data reporting protocols will decrease costs for originators, servicers and appraisers and reduce repurchase risk.”

While the work continues, the basic ability to now include a property’s spatial characteristics in a mortage transaction will go far to increase the transparency of property records as they move from the local level up to national banks and regulators and international investment firms. Standardized geographic information can reduce valuation errors, allow regulators to better understand transactions, and allow investors to better evaluate bundles of real estate investments.

 The OGC's participation in developing this standard maximizes the likelihood that applications such as Building Information Models, virtual reality and emergency response will be able to integrate foundational legal descriptions of property with other kinds of spatial information.