Demonstrating the theory and practice whereby the camera was first used for mapping (Source: HM Wilson,
Topographic, Trigonometric and Geodetic Surveying Including Geographic, Exploratory, and Military Mapping with Hints on Camping, Emergency Surgery, and Photography, 3rd Edition, New York, 1912, p. 293)
Does distance equate with objectivity?
I began working on this article to answer a relatively simple question about how we visually comprehend environmental change. In 2009,
National Geographic published an article called "
Scraping Bottom" on the Athabasca oil sands in northern Alberta. Using a set of aerial photographs taken by helicopter, the article's author indicted the developments by showing boreal forests being eradicated by massive strip mining machines. The piece set off a public debate focused on whether these pictures "truthfully" showed the oil sands as they were, or if the photographer had mediated the message through selective framing and unfairly juxtaposing content to portray the mining operations in a bad light.
Environmentalist and pro-industry groups took predictable sides over the issue. As the discussion evolved and lobbies deployed additional images and arguments to support their claims about the oil sands (as man-made disaster or well-managed development), I became interested in how both their viewpoints seemed to "elevate" as each sought a more objective visual rhetoric to make claims about the tar sands. Their efforts almost converged in space, with pro-development platforms relying on remotely sensed satellite imagery to show the extent of wetland remediation on one side, while critics used photographs demonstrating that the tar sands could be seen from space with the "naked eye" on the other — as if no further explanation were necessary.
If environmentalists and pro-industry groups could not agree on how to understand the oil sands, why could they find agreement on this other claim: that the most truthful pictures were those obtained from the farthest away? Indeed, why is it that images acquired at high altitudes are seen as more objective than ones taken from the surface of the Earth?
It turns out the answer has a lot to do with a major theme in historical geography concerning how environments are seen and represented. During the 19th century, as the Canadian state evolved and the lesser known regions of the new country were explored, maps and photographs were the primary visual devices through which geographical information about new landscapes could be communicated. Government branches like the Geological Survey of Canada and the Dominion Land Survey carried out this work, which by necessity was also conducted by sending expedition teams for months at a time into the deep interior of the continent. However, once airplanes became available in the 1910s and 1920s, the vantage for gathering knowledge and the viewpoint for seeing Canadian landscapes radically changed.
Airplanes bring about two major changes
A historical analysis is useful here since it allows a comparison of before and after a change happened. As airplanes moved explorers and surveyors into the sky, almost immediately two changes occurred:
- The first happened to photographs; a new kind of depiction emerges called the "aerial photograph." Taken from an airplane high above the Earth, these new pictures gave people a realistic vantage of the world few had seen before, and the new images soon appeared everywhere in Canada – in government reports, magazines, school textbooks – where they held out the promise a valuable new way of doing all kinds of things, from urban planning, to farming, mineral prospecting, forest management and more.
An aerial photograph on the cover of a Canadian university geography textbook(Source: NV Scarfe, GS Tomkins and DM Tomkins,
A New Geography of Canada, Toronto, 1963)
The second change happened to maps – all of a sudden the potential to survey the vast interior of Canada from the air seemed within reach. Air crews could reconnoiter in an afternoon what took teams on the ground years to accomplish. This was not possible in the 1800s, when surveying carried out on the ground was a laborious process requiring viewing instruments for calculating angles and measuring distances between points in order to plot maps. Toward the end of the 19th century, Italian surveyors realized that if you could take a photograph of the area you hoped to map, it was possible to apply the laws of perspective to calculate the same distances quickly and efficiently. The change that happened to mapping was called photogrammetry, the practice of measuring the Earth using still images.
While usefully pioneered in the Canadian Rockies during the 1880s, the flatter topography of the interior made photogrammetry impossible until the arrival of the airplane enabled surveyors to picture the ground below without needing a mountain to climb. Taken together, these changes indicate that during the 20th century, maps and photographs were brought together through this novel object called the "aerial photograph."
Many forces shape the way we "see"
Ostensibly the use of the aerial photograph as a mapping tool is about the convergence of three technologies: the airplane, the invention of photography in 1839, and the rules of perspective.
We know that during the Great War (1914-1918), great urgency was placed on the development of high-altitude cameras, faster and more efficient aircraft, and devices for translating photographic information into maps, and that with the coming of peace, these were applied to civilian use in Canada, the United Kingdom and the United States. We also know that much the same thing happened during the World War II (1939-1945) at an even greater rate. However, that doesn't really tell us much about why high-altitude imagery is thought of as more truthful or objective.
To find an answer, we can again use a historical approach. Another concern of historical geographers is being able to situate past human-environment relationships in their cultural contexts. We can think about not only the tools people used to see, but the way "seeing" itself was also something learned and practiced, or shaped by social and political forces. This requires revisiting the way people thought about maps and photographs before the airplane and the aerial photograph brought these two forms of representation together.
Listening to the 19
th-century surveyors and explorers talking about doing science reveals
these weren't just different tools for representing geography; maps and photographs also invoked different ways of guaranteeing and asserting truthful observation. On the one hand, photographic tropes embellished the characteristics of environments, very much after the landscape painting school developed in England.
Explorers took pictures of themselves and environments that helped people
understand environments by showing what it was to move through them: trekking across the prairies, paddling canoes, hauling York boats, encountering First Nations people,
clearing a path through dense forest. In survey imagery, the expertise of surveyors, explorers and scientists rested on the fact that they were there, and if they weren't in the scene, then they at least were there to get the shot. These qualities do not appear in discussions about mapping. The guarantee to truth in the map is the distanced kind of vision it offers, using a Cartesian plane and a type of projection model to capture a three-dimensional Earth in a two dimensional model, selectively representing watersheds, elevations, or land cover;
the map worked by selectively parsing different domains of knowledge.
Illustrating the procedure of taking aerial photographs (Source: GH Matthes, "Oblique aerial surveying in Canada,"
Geographical Review 16, 1926, p. 572)
The Country reduced to map form (Source: GH Matthes, "Oblique aerial surveying in Canada,"
Geographical Review16, 1926, p. 579)
Knowing the cultural context allows us to read the emergence of the new images differently. For example, when Canadian surveyors see the first aerial photographs in the 1910s and 1920s, they all make the same comment: "These are just like maps!" These statements really struck me because they reveal a prior lack of certainty about what aerial photographs would be and what types of seeing they were going to make possible. Indeed, the need to say they looked like maps makes one wonder what other things they may have looked like – why not say they looked exactly like photographs?
As it turns out, not everyone was in agreement that the new kinds of images were maps, and what kind of maps they were, if so. The majority of my article deals with the period between the 1920s and 1970s, when practitioners tried to sort out what aerial photographs were and how they should be used.
One of the main questions was whether map mosaics were the best way of recording landscape – a practice that involved flying over areas of land taking pictures at regular intervals from a controlled height, then assembling them into a montage of the geography below.
Another question was what angle to produce air photographs for use in photogrammetry. Images pointing straight down at 90 degrees appeared more like a conventional map, versus oblique images presenting Earth on an angle so you can see the landscape moving away to the vanishing point of the horizon – more in line with a photograph.
They also had questions about the interpretation of these new images.
Constructing a map mosaic (Source: Don W. Thomson,
Skyview Canada: A Story of Aerial Photography in Canada, Ottawa: Energy, Mines and Resources Canada, 1975, p. 133)
The drawback of using perspective grids to survey using photogrammetry was that the topography and character of the landscape below was not recorded. Conversely, reading aerial images as landscapes came with its own problems, since photo interpreters needed to be trained in recognition of landscape features and terrain types – many of which looked different from above than on the ground. I called the article "Canada between the photograph and the map" because the aerial image clearly invoked questions of how to frame the national environment using a new technology. Each new discussion over the nature of aerial images positioned them in terms of the prior kinds of representations: if they were like photographs, they emphasized landscapes and characteristics; if maps, distances and spatial coordinates.
When cultural context is added to historical change, what initially appears to be a new development in technology turns into a question about what kind of objects the aerial photographs are and how to look at them.
Along with how people looked at aerial images, another thing the article traces is the matter of where people looked. One of the things that distinguishes historical geographers from other historians is this attention to space and spatiality. When thinking about histories of vision, environment and science, we may give more consideration to the sites and locations where practice "takes place." Asking about how geography matters in the production of knowledge is a particularly strong branch of study in UK universities. When applied to the case of aerial photography in Canada, a trend emerges where the sites of doing science change after the airplane. The 19th-century surveying that took place in the field required teams of axe men to clear lines of sight, experts using theodolites, and travel by ox cart or river. Surveyors saw themselves as hardened by the elements, and this was important in how they were understood as experts in environmental knowledge — tropes made evident through photographs they produced on their expeditions.
The interpreter and landscape idealized (Source: Rabben, "Fundamentals of photo interpretation," in: RM Colwell, American Society of Photogrammetry, Manual of Photographic Interpretation, Washington, 1960, p. 140. Reproduced with permission from the American Society for Photogrammetry and Remote Sensing)
The airplane and the aerial photograph change all of this. A small team flies around in a plane, using a high-altitude camera that is sometimes a black box to the operators, and returns to have the images developed and plotted by experts working in the survey offices. Rather than the field, it is in the libraries and laboratories that knowledge is created through careful analysis of the images. As sites of knowledge-making changed, so did depictions of survey practice – in aerial images, the surveyors' labor and expertise was hidden from view. What this corresponds to is that as the viewpoint elevated, the surveyors themselves disappeared from the frame. For me, this went a long way to answering the question of why, as the viewpoint elevated, the objectivity or truth of the depiction seemed to increase. The higher a photograph is taken from, the more we think of it like a map – guaranteeing objectivity through the absence of human presence.
I have been using "we" think this or that about photographs throughout this paper to refer to the way many Canadians look at aerial images of the environment. Why I feel justified in making this inclusive generalization is addressed in the final section of the paper, which concerns the history of geography. Why might the people of Canada adopt these viewpoints of a relatively small group of the state bureaucrats working in cartographic surveying? The answer lies in the story of geography as a discipline.
Geographers in Canada enthusiastically embraced aerial photographs as an objective means of looking at Canada – they even splashed them across the covers of their textbooks! This really made sense, because geography was a new discipline in universities and only offered piecemeal in public schools, and geographers were searching for ways to make themselves seem indispensable and useful. They latched onto the aerial photograph as a uniquely geographical object precisely because it offered characteristic depictions of landscape at the same time as the cartographic potential of photogrammetry. Teaching people to see and interpret these became a main task of geographers, and before long classrooms were full of students sitting at rows of stereoscopes looking at image sets. In classrooms, school textbooks, and universities, aerial photographs became the preferred means of depicting Canadian environments.
Geography teaching in schools became a way of disseminating these ways of seeing to the general public.
Today, when we look at images of environments and landscape changes, we are influenced by the historical geography of the viewpoint shaped by the aerial photograph.
από εδώ https://www.elsevier.com/connect/how-aerial-photography-altered-the-way-we-perceive-environmental-change
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