SCIENCE / MEDICINE : World View : Cartographers Pursue the Ideal Earth Map

Sculptor Tom Van Sant didn’t like the look of a satellite photo map of the lower 48 states that hung in his Santa Monica studio. “Raw beefsteak,” he called it.

The map seemed rich in detail--the Mississippi River looked like an artery winding through the country--but the colors were askew. In the farm belt, where the vegetation should be lush with greens and browns, the dominant color was red because the infrared system common to satellite photography is sensitive to temperature rather than light.

Van Sant also objected to what wasn’t in the map. “Look at how Mexico and Canada are cut off as though they don’t exist,” he said. “Nobody’s dealing with the whole problem.”

The whole problem, as he puts it, is the Earth. The National Geographic Society figures that 200 world maps have been developed in the past couple of centuries, but they are essentially scientific drawings, with dots for cities, and countries or continents painted in different pastels.

Although there have been plenty of satellite photo maps of cities and countries, no one has taken on the complex project of assembling from satellite pictures a mosaic image that shows a single, clear, composite photo for a flat map of the Earth. Until now.

It is a complicated process because a single satellite photo, for all its detail, shows only a portion of the Earth. To get a complete image of the Earth it is necessary to piece together, like a jigsaw puzzle, many pictures. Finding the right pieces is all the more exhausting because two-thirds of the Earth is usually covered by clouds.

Van Sant, a map fanatic, was surprised no one had taken on the challenge. With the help of Lloyd Van Warren, a Jet Propulsion Laboratory computer graphics technician, Van Sant has spent the past year sorting through thousands of satellite pictures to find enough clear views of land to assemble a clear satellite photo of the Earth.

Their final world satellite map was completed in March and will be unveiled at Massachusetts Institute of Technology in Cambridge, Mass., on April 17. “We’ve pursued this project with a vision of allowing people to have a beautiful and straightforward image of the world,” Van Sant says.

He is not the first map maker to devise a new window to the world. The Greeks were drawing maps of the world, such as they knew it, in 550 BC. Now, with satellite photographs and vast computerized data bases, there are no secrets about shorelines, the true shapes of continents or what the Earth actually looks like.

But map makers keep designing new world maps because of the challenge of converting an image of a sphere onto a flat piece of paper, what cartographers call a projection map. “People like to come up with new projection maps now and again to try and forge their immortality,” says Robin Orr, cartography director for John Bartholomew & Son, a 150-year-old publishing house in Edinburgh, Scotland.

No matter the effort, the design is necessarily imperfect. “You can’t take a round Earth and put it on a flat piece of paper without some distortions,” said John Garver Jr., the National Geographic Society’s chief cartographer.

So map makers, like tailors, customize their work--taking in a tuck here, letting out a bulge there. World maps come in rectangles, ovals, butterflies, hearts, ellipses, stars, triangles, even stretched out like an accordion.

The most celebrated design is a rectangular world map conceived by Flemish cartographer Gerardus Mercator in 1569. The map’s signature is an exaggeration of northern land masses which are so swollen that Greenland, for instance, appears roughly the same size as North America when it is actually less than one-fourth the continent’s size.

A different view of the world is found in the north polar azimuthal equidistant projection, first devised by Frenchman Louis des Mayerne Turquet in 1648. In this map it appears as if the viewer is hovering over the North Pole with the rest of the Earth falling away in a circle, with North America on one side, Asia on the other.

Van Sant finds his project grabbing attention within the map-making community. The National Geographic Society wants to publish his satellite map in its atlas or perhaps in one of its magazines.

His satellite map is part of a far more elaborate project to create a globe 21 feet in diameter with a satellite photo glued to its surface. In his studio sits a prototype that he hopes to finish by May. Each globe will have interior lighting to picture city lights as the regions shift from day to night, while the globe spins on a motorized base to simulate the Earth’s rotation.

To recreate the image of the Earth as it appears from space, Van Sant will mount a second sphere five-eighths of an inch above the globe on which the world’s weather patterns will be projected. Weather satellites, he says, will feed data to four projectors so weather patterns can be constantly updated, accurate within 30 minutes.

In typical satellite pictures, the colors are translated according to temperature: Pale blue, for example, is not the color for the sea, it’s the color for asphalt, parking lots, industrial sprawl. But Van Sant repainted his satellite photo to capture the Earth’s subtle shades, from the light green algae in oceans to the rich golds, browns and tans of arid areas.

He imagines his globe as the centerpiece of a studio, with schools, museums and television networks as customers. Money has been a problem. NASA and the National Oceanic and Atmospheric Administration have advanced some modest contributions, but most of the project’s cash, Van Sant says, has come from his $200,000 savings.

The pictures he used were taken by satellites operated by the National Oceanic and Atmospheric Administration. The satellites follow a polar route--north to south--and with the Earth spinning below them, after enough orbits the satellites have blanketed the globe while transmitting pictures in digital form.

Van Sant hunted though thousands of photo negatives at a government library before buying about $10,000 worth of satellite computer tapes. The tapes were filled with seven days of photos taken over two years and picked because on those days the cloud cover was thin.

He assembled one cloud-free composite photograph by laying photos of the same spot of the Earth on top of each other in a graphics computer. Piece by piece, bits of land were revealed. The final picture will be printed on 36 strips of ultra-thin film paper, then stretched onto his globes.

Finishing the flat map, however, requires another step. Van Sant has been working on two pictures. One is a three-dimensional photograph of the Earth that will be printed in 36 strips and then glued onto his globe. That picture will give the truest image of what the Earth looks like. But to have a picture that fits onto a flat piece of paper for his world map, Van Sant’s computer had to convert the three-dimensional image into a rectangular shape, much like the old Mercator design.

To the dismay of geography teachers, the Mercator remains the most common world map sold in American bookstores. When the spokeswoman at the State Department in Washington takes the podium, the Mercator map is her backdrop. “The Mercator is something people have burned inside their minds. For them it’s the way the world is supposed to look,” says Garver of the National Geographic. “But the Mercator map was never intended to be used as a world political map.”

Mercator’s remarkable invention solved the problem of long distance travel. Navigators can draw a straight line in any direction on his map and it will represent a constant compass heading. But to manage that, the farther a point is from the Equator the more Mercator stretched and exaggerated the land masses. In the 1700s, as European nations expanded their empires by sea power, the Mercator was such an essential navigational tool that it slowly became accepted as the view of the world.

The National Geographic Society, which distributes 11 million world maps each year, does its best to make people forget the Mercator by endorsing other designs. In 1922 the Society picked a pumpkin-shaped map by a Chicago engineer, Alphons van der Grinten, who lessened some of Mercator’s distortions.

Two years ago the Society settled on “a more realistic” world map developed by Arthur Robinson, a retired cartographer from the University of Wisconsin.

Robinson, now 75, developed his map in 1963. “I decided there ought to be another way of balancing out the various distortions without doing it mathematically,” he said. So Robinson tinkered with a map to design “the best portrait that I could,” then worked out the mathematics.

His map is elliptic, “to give the impression it’s a round Earth we live on,” Robinson says. He drastically shrank the Soviet Union, which appears more than twice its relative size on Van der Grinten’s map; on Robinson’s map the country is a mere 18% bigger than its proportional size. But he was democratic in his tailoring: he shrank the United States so it appears 3% smaller than its “true” size.

The National Geographic Society hailed the Robinson map as a great step forward, and the Pentagon keeps a Robinson map in its briefing room. But despite the Society’s imprimatur, the map has not caught on everywhere. In Scotland, John Bartholomew & Sons decided to stick with its 35-year-old world map, saying the Robinson makes no great improvement.

Even some Americans objected to the Robinson map. Garver was flooded with letters by admirers of the late R. Buckminster Fuller, the engineer and inventor with a fondness for geodesic domes, who developed his own, predictably distinctive, map in 1943 called the Dymaxion AirOcean World Map.

The Fuller map is centered on the North Pole with the rest of the land areas spilling out in several directions, resembling a skinned animal. He laid out his map in 22 triangles so that if it were cut it would more or less fold into a globe. “It’s the only flat map without distortion in size or shape of any land areas,” says Fuller admirer Kiyoshi Kuromiya. But the printing on Fuller’s map runs in dozens of directions, requiring the reader to constantly rotate the map. Robinson says: “As a world map it’s a disaster.”

For Americans, perhaps the most startling design is a series of upside-down world maps. Stuart McArthur, a cartographer in Melbourne, Australia, had been frustrated that most maps place the Northern Hemisphere on top. In 1979 McArthur got his revenge, completing a map in which Down Under is up yonder.

In the world according to McArthur, Australia is smack in the top center, with South America off to the left, shaped like a turkey drumstick that points up toward Antarctica. McArthur has sold 190,000 maps--to Japanese tourists, the Soviet Union, Great Britain, New Zealand. Robinson says upside-down maps “seem funny simply because we’re so used to another orientation. But there isn’t any up or down in space.”

Of all recent world maps, none matched the impact of one unveiled by West German Arno Peters in 1973. Map makers accused him of lies, distortions, even plagiarism. Still, 17 million copies of the Peters map have been sold in six languages and it is especially popular in the Third World.

Peters got the idea when writing a history book and was dismayed that other volumes emphasized major countries while overlooking many smaller nations. He wanted to include an atlas but, Peters said, “I found they all lie. I wanted to have a map of equality and I had to put it together myself.”

He set out to overcome what he says is the European bias of map makers, dating back to Mercator, which exaggerates the Northern Hemisphere’s prominence. If nothing else, Peters’ map looks radical, the continents slim and elongated as if Amedeo Modigliani painted them. Africa and South America seem especially enormous.

Peters’ is an equal-area map, so-called because the land masses are correct in their total size relative to each other. Every map maker must choose a true point of reference--in Peters’ map this is a line running parallel to the Equator halfway between the Equator and the North Pole--and the farther from that line, the more distorted are the land shapes. Peters picked this reference point in an attempt to balance out the polar distortions on his map, but Africa and South America ended up being so distorted that many cartographers despise his map. Scholars, including Robinson, have pointed out that Peters’ map is virtually identical to one devised 135 years ago by a clergyman.

Robinson doubts there are any innovations left in projection maps. “We’ve got enough,” he says.

Van Sant, of course, sees his satellite map as a major breakthrough. “It’s the first new map of the world in a few hundred years,” he says. “There will be no reason for anyone else to do one.”