Tucked away on the University of Maine campus is a treasury of film that chronicles New England’s landscape from 1946 to 2015. We’ll hear from the researcher who is digitizing thousands of aerial photographs and making them accessible online. What can these photos tell us about the history of Acadia and how can they influence the future of land stewardship? Find out on the season three premiere of Sea to Trees.

University of Maine Sewall Company https://digitalcommons.library.umaine.edu/sewell_aerial/

Title: Past, Present, and Future | Historical Aerial Photography

Transcript : Balloons, pigeons, and kites. All three of these objects have served as vehicles for aerial photography. In 1860– floating high above the city of Boston in a hot air balloon– James Wallace Black took one of the first successful aerial photographs. He titled it “Boston as the eagle and the wild goose see it.” Taken only a year before the start of the Civil War photographs like Black’s would become a staple for military reconnaissance.

By the turn of the twentieth century, Lt. Hugh D. Wise had built an eighteen foot high kite with a box camera attached to it and the German inventor Dr. Julius Neubronner strapped cameras to the chests of pigeons, turning them into avian paparazzo and releasing them throughout the country.

{Pigeon flutter}

After the Wright brothers first successful flight in nineteen- oh three cameras started to make their way into airplanes, becoming tools for information in World War One and World War Two.

{Music}

But military intel wasn’t the only use for this burgeoning field. Scientists started using aerial photographs to understand difficult to reach geological formations like glaciers and volcanic craters. Archeologists began to see ancient works– like the Ancestral Pueblo ruins of the southwest– from a different point of view. And the damage from natural disasters like earthquakes and floods became easier to assess.

Sea to Trees is brought to you by Schoodic Institute at Acadia National Park. I’m Trevor Grandin. In this episode we’ll delve into the past to understand how a collection of aerial photographs once stored in a library annex are being unearthed and how they could help tell the story of modern Maine.

{Pause}

Peter Howe’s face is positioned inches away from a brightly lit table on the third floor of the University of Maine’s Fogler Library. Behind a locked door in the special collections section, two negative aerial photographs of the Schoodic Peninsula are side by side and backlit.

{HOWE}: “This... this one here… what’s the date we have on this one? This is nineteen-fifty-five... so one-hundred-and-twenty-five... this was one of the largest surveys we have on record... the eastern corporation. This survey… so there were nine rolls of film... oh here we go… (fade)”

The black and white photos capture a birds-eye view of the peninsula, allowing us to study the layout of Acadia on August twenty-fifth, nineteen-fifty five. Like Peter said, these photos are part of film roll number one-hundred-and-twenty-five, a series of aerial shots of Downeast Maine produced for the Eastern Corporation, a paper manufacturing company that once controlled large swaths of spruce forest throughout Maine.

Roll one-hundred-and-twenty-five is a tiny part of a much larger collection held within UMaine’s Special Collections. This treasure trove of aerial photography consists of almost three-thousand canisters of film.

The photographs were donated by the very organization that took them, the James W. Sewall Company. Sewall’s primary directive was forestry and civil engineering. This manifested as mill operation inspections, timber appraisals, fire protection, and large scale land surveys. An early promotional pamphlet lays out their purpose to prospective clients.

{Wood chopping and trees falling} {Music}

{Character voice over}: “Thanks to modern forestry knowledge and methods... the possible increase in the value of forest and timber lands can now be estimated with remarkable accuracy… You already know that all wooded lands are steadily increasing in value; we want you to realize that practically all these wooded lands can be appreciably enhanced in value under careful management... and that it is our business... as practical foresters... to achieve the best possible results along these lines for our patrons.”

As technology advanced, Sewall’s operations grew wings and the survey process took an aerial approach, beginning in 1946.

{Propeller plane taking off and circling}

For almost seventy years, organizations like the Eastern Corporation, Maine Department of Transportation, and even the National Park Service hired Sewall to fly over land in their jurisdiction and take survey photos. Equipped with a pilot and a camera operator, the small propeller planes buzzed along the landscape. A camera, like an overhead projector without an arm, poked out of a fitted hole in the plane's body and pointed at the ground.

{Camera shutters}

The camera operator sitting next to the machine – shutter button in hand – snapped photos at specific moments in the air, producing a quilt of images waiting to be stitched together later. The collection includes surveys from Maine, Massachusetts, New Hampshire, Vermont, New York, and even Vietnam during the Vietnam War.

Many organizations wanted to understand what types of vegetation were present and in what abundance. Some flights took place during specific seasonal or weather events like leaf offs or strong ice storms. Eight years after a fire burned over seventeen thousand acres of land on Mount Desert Island, a survey crew documented the newly grown forests of birch and aspen trees that took hold after the blaze.

All taken at different points in time spanning from nineteen-forty-six to twenty-fifteen, these photographs illustrate how a landscape can change, both naturally and through human intervention. That’s where Peter Howe comes in.

Peter is a PhD student in the University of Maine’s School of Forest Resources and an Acadia Science Fellow. He’s using this collection of photographs for his own research while trying to make it accessible for the public. Working with library specialist Paul Smitherman, Peter is taking a multistep approach to his research.

{Howe}: “Ya know… my little piece of this project has many parts. Like definitely the big collaborative first step that I’m working with Paul on is we just need to get a lot of this digitized because just a small fraction of the archive has been digitized at this point… and then getting them stitched together into these georeferenced mosaics that we can compare to the modern landscape and modern imagery. Then from there, looking closer at the forest and trying to understand forest change across time which is where I’m hoping to do more GIS analysis.”

And that first step – the digitization – may be Peter’s largest step.

{keys jingling and unlocking}

Because behind the locked doors of the special collections storage lies a small fraction of his work.

{HOWE}: “This is what… one percent of everything… fades.”

This one percent of the film collection takes the form of two floor to ceiling, long metal shelves filled top to bottom with jet black canisters. Each canister is about the height of a roll of paper towels and weighs over fifteen pounds. A bright yellow Kodak sticker swiped across the front of the canisters identifies them as infrared aerographic safety film.

The tops of the canisters are labeled with their respective numbers, the organization that commissioned them, the date they were taken, and their scale. The other ninety nine percent of the film is stored in a University of Maine annex across campus sitting snugly on rolling library stacks.

{rolling shelves}

{HOWE}: “Somewhere up there is the number five canister… probably on that top shelf. That’s nineteen - forty nine. It would be some of the earliest.”

Prior to Peter’s research, Smitherman was manually scanning in film as it was requested. If someone asked for photos, for example of Hancock county, he would scan a couple and send them on their way. Using this manual scanning process it takes about ten minutes to upload one roll. With over three thousand canisters in the collection it would take over twenty days of continuous, around-the-clock scanning to digitize every roll. Thanks to funding from the Northeastern State Research Cooperative and Acadia Science Fellowship the project now has access to an automatic scanner.

In its idle form the UltraScan 5000 looks like a powder-blue pancake griddle. Taking up the entire table top, the heavy rectangular machine’s lid has two black, plastic coverings on either side. Lifting the lid illuminates what’s hiding under those exterior coverings. Two black batons – like plastic rolling pins – hold the film rolls and gently rotate, spooling and unspooling the negatives over the glass scanning table in the middle. Load the roll up, let the spokes rotate and they scan the photos automatically.

Although the scanner is an obvious upgrade, it comes with its own set of quirks. Made in nineteen-ninety nine, the model was discontinued in the early two thousands. Consequently, there is no technical support that goes along with the scanner and no updates for its software. Without updates the scanner can only run on Windows XP, an operating system that works on a choice number of older computers.

{HOWE}: “So we had to find a dated computer that wasn’t too fast but wasn’t too slow and then using this software that hasn’t been updated because they stopped making it back in two thousand.”

Scanning a whole roll of film manually wouldn’t be such a big hassle if they only had a couple photos inside but each roll of film comes with around two hundred and fifty negatives. The rolls also contain an important component for interpreting the photos: a flight index.

{HOWE}: “So with each photo survey they would produce these maps… it’s a photo index that shows where each photograph was taken and so these are the flight lines that the pilots flew. And so they would fly in this very regular patterned route and part of that is because they really wanted to ensure that they captured every square inch of the land that they were surveying but also that there was overlap between photographs because even back then they were doing and earlier version of photogrammetry that is what I’m doing today.”

Photogrammetry, a word from Greek, can be broken down into three parts. Phos,meaning light; gramm, meaning drawing; and metrein, the noun for measure. Put simply, the process of measuring an object using a photograph.

A more complicated explanation comes from the National Oceanic and Atmospheric Administration. Photogrammetry is a method of approximating a three-dimensional structure using two dimensional images. Photographs are stitched together using special software to make the 3D models and photomosaic maps. This method of measurement can be used to map topography, model shipwrecks, statues, and even large scale forests.

{HOWE}: “So there’s kind of two outputs that the photogrammetry process can produce and that’s… one, being an orthomosaic, that’s this stitched together composite image and then the other being this actual three dimensional model of what’s in the photographs. So it’s really amazing that we can get a three dimensional model of the historical landscape that even captures tree height, forest canopy height back in time.”

After the scanning process, these aerial negatives are uploaded into Peter’s photogrammetry software and put together along overlapping edges. The map that’s created is a tapestry of negative photographs for a specific region during a specific year. Processes like Peter’s – digitizing and uploading historical negatives – have been happening for a while.

{Halsted}: “We’ve had printed air photos here for years… probably since the 1980s.”

That’s Christian Halsted, director of earth resources information at the Maine Geological Survey where he’s in charge of the aerial photograph collection.

{Halsted}: “Obviously they sit in filing cabinets and you kind of have to know to contact us to come in and look at them. We recognized that they weren’t getting a lot of use because they were sort of a hidden treasure, a hidden resource.”

After receiving USGS funding to digitize their collection, Maine Geological Survey created their own interactive map. There are many similarities between their map and Peter Howe’s atlas. Both collections are made of photographs produced by the Sewall company, both are for public reference at any time, and both can be filtered by year. But they’re distinct in important ways.

{Halsted}: “We didn’t georeference each individual photo into a mosaic like you would think of… like google maps… like a seamless photo layer but what we did was we geolocated each photo. When you zoom in an area and you click on it you basically just get the photos that overlap that area that you clicked on and then you can review them individually and see if one or multiple of the photos are the ones you’re looking for.”

But Peter’s project goes a step further than scanning and uploading. To tie these historical photographs to the present Peter clicks through every negative and places a “ground control point.” These points are primarily located on objects and features he knows haven’t moved since the photographs were taken.

{HOWE}: “A good point would be a great rock, or a farmhouse, or a bridge, or a road intersection. Something that really clearly comes to a point that’s exposed, that we know won’t be later covered by canopy and things that we’re really sure haven’t moved.”

Once these control points are established in the historical photographs, the computer finds those unmoved points in modern satellite imagery allowing for an almost seamless overlay of historical and current imagery.

The product? The Northern Forest Historical Atlas. A site similar to Google Earth but where many are used to seeing the emerald expanse of Maine, black and white TV static has taken its place.

{Radio Static}

Zoom in a little further and the static morphs into pockets of historical photographs intermixed with current satellite imagery. Film is still the ideal way to capture aerial photography in many ways. Film resolution is so clear that you can drop into individual streets with almost no loss of clarity, at higher resolution than the digital cameras many use today.

Looking at Bar Harbor while flipping between historical and present photography uncovers the buildings, parking lots, and roads that were or weren’t present in nineteen-sixty six. Across Mount Desert Island, the ponds and lakes grow and shrink from past to present suspended at the exact height they were in nineteen-fifty five.

This unique perspective can foster a change in spatial understanding. Individual environments and landscapes that are often only seen from eye-level are looked on from up above. Roads that often seem so permanent and reliable are shrunken into small veins that snake throughout wider wilderness. From ground-level our world is relegated to what is directly around us, but the aerial photographs reaffirm our understanding of nature’s connectedness. And as more film rolls are scanned in and geolocated the historical layers to choose from will only grow expanding their uses.

{HOWE}: “You know, I’m working with a few foresters who are interested in the logging history, the forest disturbance history in the land that they manage. Understanding successional change, understanding fire histories, understanding insect and disease histories.”

The aerial photography that Peter is digitizing will be of use to those right here in Acadia National Park. Restoration work on the summits of Acadia’s mountains is seeking to revegetate areas worn down by visitors and natural erosion. Thousands of pounds of soil have already been trekked up to the top of Sergent and Penobscot mountains with the hope that plants will take hold once again.

{Wheeler}“As we move forward and get more iterations of aerial photography and remote sensing data from now on., that's going to help us in kind of having a big picture monitoring of and tracking of progress as we restore square footage or square meters or…how much area right are we restoring to vegetation.”

That’s Jesse Wheeler, vegetation biologist at Acadia National Park. He leads many of the park's invasive species management programs and his team plays a big part in revegetating the summits of Acadia. Throughout its history different approaches have been taken to manage Acadia’s plants, especially on mountain summits. Studies that involve remote sensing and aerial photography have already proven beneficial to park managers like Jesse.

In 2022, John Daigle of the University of Maine and Min-Kook Kim of Marshall University used satellite imagery to analyze mountain summits throughout the park. They determined what areas had seen growth during restoration efforts and what areas were still under stress creating a better picture for Acadia’s present. Paired with Peter’s historical photography, these studies could greatly impact restoration efforts all around Acadia.

{Wheeler}“And so being able to have some scale monitoring of what's going on up there as we're putting forth all this effort and resources is can we track that over time? And I think a great way to do that is using aerial photography.”

The possibilities are endless for Peter’s work with organizations and individuals all over the place wanting a piece of what he’s creating. MGS’ Christian Halstead explains how varied the uses have been for the geological survey’s collection.

{Halsted}: “We all, as soon as we get our hands on a map, whether it’s digital or in paper format, we go and look at our house or our property. So I've had a lot of people call and describe a situation where their grandparents owned a farm somewhere in the last half of the last century and they’d love to have a picture of what that farm looked like in 1950 when their grandparents were working on it or something like that… Quite frankly, we use the photos ourselves within the Maine Geological Survey. Questions around changing sea level and shoreline changes and movement of bluffs and dunes and coastal erosion.”

Whether it’s for ecological research or personal interest, access to these historical photographs helps us better understand our place in history. To some the outcomes of past actions seem so set in stone without visual evidence, so certain. What a landscape looked like before a life-altering fire, mountain summits prior to intensive use, or townships before urbanization. There was a time before these events and structures. They’re not as permanent as many think. Peter Howe again…

{Howe}: I like the term historical ecology because it’s all about bringing together what we might call natural and human histories and really understanding those as totally intertwined, not separate histories but these very interconnected histories that have shaped each other across time.

{Pause} {End/transition music}

Join us for the next episode where we’ll continue the exploration into Acadia’s past through the birds. And the groundbreaking research that happened in the park’s forests.

{Kaspari} “The Warblers of the East were just utterly gorgeous, utterly captivating. They literally looked like Christmas tree ornaments. They were just painted in different ways…”

Thank you for listening to Sea to Trees, a podcast from Schoodic Institute at Acadia National Park. Acadia National Park is on the traditional lands of the Wabanaki, People of the Dawn. This show was made by Trevor Grandin, the Cathy and Jim Gero Acadia Early-Career Fellow in Science Communication. Catherine Schmitt is our senior editor. The cover art was created by Sarah Luchini. Special thanks to Peter Howe, Paul Smitherman, Jesse Wheeler, and Christian Halsted for sharing their expertise with us.

This podcast is possible with generous support through The Cathy and Jim Gero Acadia Early-Career Fellowship, a partnership among Schoodic Institute, National Park Foundation, and National Park Service.

As a nonprofit partner of the National Park Service, Schoodic Institute inspires science, learning, and community for a changing world. To learn more, visit schoodicinstitute.org.