Parcel boundaries need to be evaluated differently from ordinary attributes.
Evaluating parcel-boundary quality therefore means looking at source, validation, spatial context and intended use — not simply whether the lines appear to match an aerial image.
A buyer should understand where the geometry originated, what validation has taken place and what the provider does when spatial problems appear.
Regrid relies on authoritative parcel sources and documents several parts of its geometry-processing methodology, including checks for county completeness, correction of common polygon problems and handling of larger spatial issues.
Regrid also does not simply move parcel boundaries to match aerial imagery or another basemap. Imagery itself can contain spatial inaccuracies, and aligning parcel geometry visually to a particular image does not necessarily make it more accurate.
When comparing providers, ask:
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- Who created or maintains the underlying parcel geometry?
- What validation is performed?
- How are invalid geometries handled?
- What happens when a larger spatial problem is identified?
- Does the provider alter authoritative parcel lines to match imagery or another basemap?
- Is the level of precision appropriate for what we need to do?
It can be tempting to judge parcel geometry visually by comparing it with aerial imagery. However, the fact that a parcel line does not appear to align perfectly with an image does not, by itself, tell you which dataset is wrong.
Most parcel geometry originates with local sources. Those sources may have access to different levels of positional precision and different imagery for georeferencing their parcels. That imagery is not always mapping-grade orthorectified imagery, which means spatial error can sometimes be introduced at the source.
The imagery used later to view or evaluate those parcels can also contain positional error. In those cases, an apparent misalignment may be caused partly or entirely by the imagery rather than the parcel geometry.
This matters because people naturally tend to trust what they see in an image. A visual overlay can be useful for identifying something worth investigating, but it should not be treated as proof that the parcel boundary is incorrect.
It’s very important to remember that parcel data is not survey-quality data and no GIS parcel data should be treated as a substitute or replacement for a professional survey.
While useful for mapping, analysis, property research and understanding the spatial relationship between parcels it should not be relied on for legal boundary decisions, final placement of people or personal property on a parcel, or property conveyance.
Where the exact legal location of a boundary matters, the appropriate next step is to have the property surveyed.
🔗 Learn more: How should you evaluate parcel boundary quality?