![]() ![]() One labor-intensive method invented in the 1920s, the so-called Wenschow technique, involved carving a plaster terrain model then photographing it. “Real-life lighting involves light bouncing off one surface onto another.” Capturing that play of light can make a terrain map look more realistic, he says.īut in the days before computers, cartographers often went to great lengths to get the illumination right. Daniel Huffman goes even further, using 3-D modeling software to mimic the way light bounces around a scene. These days the angle of illumination and other features that affect the perception of depth can be easily tweaked by computer (you can play around for yourself on this online map Jenny developed). In a study published earlier this year, two researchers based in Switzerland, Julien Biland and Arzu Çöltekin, showed terrain images with differing angles of illumination to 27 volunteers and came up with a remarkably precise estimate of the optimal angle for reducing this optical illusion: 337.5 degrees, just a bit to the north of the 315 degree northwest lighting cartographers have traditionally used. The reason remains mysterious, but you can see an example of this in the side-by-side images below. But the Swiss cartographers knew that the human brain is easily fooled into confusing ridges and valleys on maps and satellite images unless the illumination comes from the northwest. Switzerland is in the northern hemisphere, which means the sun always appears in the southern sky. If you think about it for a minute, that’s very odd. ![]() ![]() In the image above, the main source of illumination comes from the northwest. Imhof and his Swiss contemporaries were also masters of illumination. You can see this approach at work in Imhof’s shaded relief of Graubünden, Switzerland, below. “The highest peaks are closest to the viewer, so they’re depicted with the highest contrast, while the lowest valleys are farthest away, so they’re depicted with the lowest contrast,” Jenny says. Imhof tried to imitate that effect by giving the viewer an aerial perspective, as if looking down on the terrain as from a satellite or airplane. One of Imhof’s greatest contributions, Jenny says, sprang from the realization that when you stand on a mountaintop looking toward the horizon, closer peaks appear sharper than distant peaks due to atmospheric haze. Imhof literally wrote the book on shaded relief-his Cartographic Relief Presentation, originally published in German in 1965, is still essential reading for cartographers (it was also the main source for the brief history above). Many of these were invented by Eduard Imhof, a professor at the Swiss Federal Institute of Technology in Zurich. The Swiss made several innovations in that era that are still used by cartographers today, says Bernhard Jenny, a cartographer at the Royal Melbourne Institute of Technology in Australia. Cartographers today refer (somewhat dismissively) to mountains depicted this way as “woolly caterpillars." You can see a later example of this in the 1807 map below of the Mexican volcano Pico de Orizaba. One method, called hachuring, used lines to indicate the direction and steepness of a slope. And mapmakers developed new methods for depicting terrain. Topographic surveys were done for the first time with compasses, measuring chains, and other instruments, resulting in accurate measurements of height. Over the subsequent centuries, mapmakers made mostly subtle improvements, varying the size and shape of their mountains, for example, to indicate that some were bigger than others.īut cartography became much more sophisticated during the Renaissance. It’s an effective symbol, still used today in schoolchildren’s drawings and a smartphone emoji, but it’s hardly an accurate representation of terrain. One of the oldest surviving maps, scratched onto an earthenware plate in Mesopotamia more than 4,000 years ago, depicts mountains as a series of little domes. The best examples of this work use a combination of art and science to evoke a sense of standing on a mountain peak or looking out an airplane window. ![]() This poses a problem for mapmakers, who typically only have two dimensions to work with.įortunately, cartographers have some clever techniques for creating the illusion of depth, many of them developed by trial and error in the days before computers. From the soaring peaks of the Himalaya to the vast chasm of the Grand Canyon, many of the most stunning sites on Earth extend in all three dimensions. The world’s most beautiful places are rarely flat. ![]()
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