Borough rolls out 1,000 square miles of new aerial maps

A set of new aerial maps released this week on the Mat-Su Borough’s website aim to give residents and officials a better look at development land use and access.

The new maps are the first batch in a set of three installments planned for updates between now and 2021, said Heather Kelley, a Geographic Information Systems (GIS) specialist with the borough. Documenting 1,152 square miles, the new maps show the region’s most populated areas, including Point MacKenzie, Knik, Big Lake, Houston, Wasilla, Palmer, Butte, Hatcher Pass, Sutton, Chickaloon, Glacier View and Eureka, officials said in a release.

The maps refresh a collection made in 2017. Prior to that, updates were made less frequently, Kelley said, with the other most recent one finished in 2011. A comparison of those two sets and the region’s population growth – about 2.1% just between 2018 and 2019 – made officials realize that going forward updates are needed much more frequently.

“What we realized was that that was a pretty significant gap for our populated areas, and it was pretty remarkable how much was changed” between 2011 and 2017, she said. “It’s what ushered us into this new plan, and we’re trying to get populated areas done every three years.”

Now the update schedule calls for maps to be redone on a rotating basis, with the most populated areas refreshed every three years and a third, less populated, region rotated in after that.

In 2020 the new collection will focus on an about 1,000 square mile area over the Parks Highway corridor, and in 2021 officials will collect images over an additional 1,159 square miles around Petersville Road, Oilwell Road and Susitna River. The schedule will reset in 2022, with new imagery once again done over two years of the most populated regions. The third year, however, will then focus on a different, more rural, region.

“That third area is going to be floating around,” Kelley said. “It will be an area where we haven’t had imagery in a long time, a natural resources management area or … areas where our population is at least for recreational purposes.”

The imagery is relied on heavily by emergency dispatch officials to help direct responders, Kelley said. The GIS office also uses it to keep other Borough information, such a road names and subdivision locations, up to date. It’s needed because other mapping services, such as Google, simply don’t update their often enough to reliable. The latest Google aerial map update, for example, was in 2011, she said.

The maps are made by borough contractor Quantum Spatial, which has an office in Anchorage, Kelley said, and cost $88 per square mile. That’s a price tag of about $101,400 for this year’s map update.

Capturing the perfect images can be really tricky around Alaska’s weather, she said. Ideally, the images, which are taken from a plane, are done after snow is gone but before the trees have a lot of leaves so that they can have the best possible view of trails and roads – a very short window of time. In 2019, she said, the collection window was focused on late April and early May, although some high elevations weren’t finished until mid-July due to snow.

While the photos are detailed, clearly showing vehicles parked in driveways and patio tables on back porches, they aren’t clear enough to see people, she said. That’s because each photo pixel is equal to a one-by-one foot or one-half-by-one-half foot area on the ground.

“It’s just not a small enough resolution that you’re going to be able to pick out people,” she said.

Anyone can view the maps on the borough’s website by searching the parcel map and selecting “2019 imagery” from the menu. [link to https://mapping.matsugov.us/Html5Viewer/index.html?viewer=MSB_Parcel_Viewer]