Parcel (cadastral) boundaries are great! Yup, *private* property

[Minh_Nguyen (Minh Nguyễn)]

@osmuser63783

Not as an import but as a layer to be enabled in editors when mapping other things that are verifiable on the ground, such as leisure=garden garden:type=residential with a barrier=fence/wall/hedge in between them.

In Santa Clara County, California, around the corner from where @jidanni was looking on Google Maps, we’ve been referencing the county’s official GIS parcel layer when mapping shops and other POIs – not for the property lines per se, but rather to match addresses to the external dataset. Sometimes parcels have unintuitive shapes, so it isn’t enough to cross-reference a house number that’s floating about the parcel’s centroid.

@Minh_Nguyen

For the most part, you and I can probably shrug at the Board for Professional Engineers, Land Surveyors, and Geologists when armchair-mapping California’s streets and rivers, but do we really want to push the boundaries with bespoke property line mapping? Most of us don’t hold a surveyor’s license and can’t afford one.

Perhaps this was too subtle, so I’ll try again: the California state board responsible for issuing surveyor’s licenses has been fining unlicensed individuals for authoring and distributing maps that purport to depict property lines. In Crownholm v. Moore, an entrepreneur had made a business of drawing site plans for residents (to submit to their local authorities for permitting) by tracing the property lines off of Google Maps. The board ordered him to cease and desist and pay a $1,000 fine because he was unlicensed. With the help of First Amendment advocates working pro bono, he challenged the board’s ruling in federal court – and lost.

I don’t know where that case is headed next, or to what extent it applies to the kind of mapping being proposed here. But I personally wouldn’t want to jeopardize our scratch-made, free-range craft mapping for the sake of something that the public can already obtain elsewhere as open data. The most we’d do with the Santa Clara County parcel layer would be to make sure our landuse areas are consistent with the property lines, but we wouldn’t try to reproduce the property lines as such. We shouldn’t give users the impression that we’re trying to collect that kind of information.

Property lines are sensitive because they’re statements of ownership. People have gotten in trouble for misrepresenting ownership of land. That’s why the process for becoming a professional land surveyor is so involved. Even the county agencies responsible for maintaining these parcel layers and collecting taxes based on them insist that you respect their disclaimer of warranty, regardless of the data’s license.