Heard a plane flying over your house lately?

 June 27, 2024 Read online A newsletter for the people (and turkeys) of Cambridge and Somerville. No question about it: It's Thursday.The flight path of a Bluesky Geospatial plane last week as it took many images of Cambridge. (Courtesty FlightAware)If you saw a low-flying plane zipping back and forth across Cambridge and Somerville on a certain day last week, and feverishly wondered if the government might be gathering data about your neighborhood — you were 100 percent right.

On June 19, a plane hired by the City of Cambridge was capturing super-high-resolution images of the city to help it plot out its fight against climate change, among other efforts.

Cambridge has long had a team devoted exclusively to dynamic maps called Geographic Information System or GIS. The city uses the map technology across pretty much every department. It runs the gamut from police crime analysis to modeling how future rainstorms might flood low-lying areas to property tax assessing, and keeping track of the city's 20,000 or so public trees.

I had a lot of questions, so I got on a video call with Jeff Amero, who has overseen the city's GIS efforts since 2001. We chatted about raster analysis, photogrammetry, and shapefiles, yes, but also the power of a map to answer residents' pressing questions.A 3D map of a part of Harvard Square that uses data from low-flying flights. (City of Cambridge)Amero told me last week's low-flying plane took photos to update the city's base maps on which other data is added. And the flights are key to keeping the anchoring data fresh.

"Even though we're only seven square miles, we're a very dense city, and there's a lot going on in those seven square miles!" he said.

The flight also used something called LiDAR. Data from it are classified to show what's on the ground: water, road, vegetation, etc. With everything in bloom at this time of year, he said what the flight got will be helpful to create a map of the city's tree canopy, and do a shade analysis. That seems extra important in this summer of heat.A tree map with specific tree data in East Cambridge. (City of Cambridge)Amero told me the first flyover for a Cambridge GIS map was in 1995, and that was used to create a sewer and stormwater map, a water distribution map, and a map of tax parcels. From there, they just kept building out new maps, from zoning to public safety.Parcels near Massachusetts Avenue. (City of Cambridge)I took a course in college and one textbook was titled "How to Lie with Maps." A key premise was that all maps are a lie in some regard: putting a three-dimensional world into two dimensions requires distortion. I asked Amero his take.

He laughed and said he found that book really interesting. He said the city has leaned into making all the information it has publicly available, and totally transparent.

"Before, if we had the parcels, and somebody wanted to use those, they would have to go to the assessing office and ask for a file. Now, they can just go to the open data portal," he said.

"We don't put out anything to confuse; we actually hope to do the opposite. We try to empower anybody that's going to our website with as much information as they can use."

And that, I suppose, puts a different spin on a government-contracted plane taking a picture of your house.

Joshua Miller
Assistant Metro Editor