Structure / Building Footprints FAQ

Q: How is the building footprint product collected?

There are many different sources for the data. Some of that is automated much like our parcel harvester and others are manual. 

Sources (Some examples, but not limited to) 

• State government 
  • E911, Address Info, Buildings 
• County government 
  • E911, Address Info, Buildings 
• City government 
  • E911, Address Info, Buildings 
• Open data portals
• Manufactured 
  • This is done through LiDAR and Image extraction, for all  our LiDAR manufactured data we carry height and ground elevation.  

Q. Is any open source data used in your product. Example Microsoft, or OpenStreetMap? 

A: OSM or Bing building footprints are not used in our product. 

Distinguishing characteristic of what we will not use are:

• If a source comes with a ODBL data license which is an open license however puts significant burden on commercial use. Improvement and redistribution.
• Any data source that expressly prevents redistribution.  

Q. How is the ground elevation determined? 

A: Using LiDAR (Light Detection And Ranging) Image Processing. LiDAR has become an established method for collecting very dense and accurate elevation data across landscapes. The active remote sensing technique is similar to radar but uses laser light pulses instead of radio waves. LiDAR is typically flown or collected from planes where it can rapidly collect points over large areas.  

Source: https://coast.noaa.gov/data/digitalcoast/pdf/lidar-101.pdf

Q. Is a single building made up of a single geometry or multiple geometries? (building with multiple heights) 

A: A single geometry. We carry a min/max and average building height attribute.

Q: Do buildings come from a county source? Or are these based solely off satellite/lidar imaging? 

A: See the first FAQ on this page

Q: Do we have buildings that do not have a link to parcels?

A: Yes, there are areas where we have building footprints and we have not yet identified a parcel source.  This can happen in a couple of dozen counties for which we do not have parcels, and there are some counties where we have parcels. However the parcel data can be missing or trivial, e.g. a county w/ a Native American Land may be missing parcels for the NAL, or some areas of Maine are missing parcels in very rural areas.