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www.c-tug.net Phone Toll free: 1-877-231-5711 KanuLock-US-AD-Kayak2.pdf 1 28/06/13 3:54 PM TECHNOLOGY BY DAVID JOHNSTON YOU ARE HERE
EXPLORING THE CHANGING LANDSCAPE OF MAPMAKING
Maps and charts are magical pieces of paper. Layered with a wealth of information, they can tell us everything from what kind of scenery to expect to where to camp and when to paddle. They can be a source of inspiration, or show you the way home when you are lost. Maps are truly the backbone of any trip, but rarely do we give much thought to how they were created, or by whom. Maps have been around since at least 2400 B.C.E. when they were used in Mesopotamia
to show property boundaries for taxation purposes. These maps were largely inaccurate, however, as their creators struggled to draw a bird’s-eye view without leaving the ground. It wasn’t until 1539 when Dutch mathematician Reiner Gemma Frisius developed a sur-
veying method of dividing an area into triangles—triangulation, as it’s known as today— that cartographers could begin to map large areas with much greater accuracy. It was another Dutchman who first employed concentric lines, or contours, to show areas of equal water depth in 1727. Still, topographic maps using contour lines to represent land elevation didn’t catch on for another 150 years. In North America, most early maps were developed by laborious land surveys. Teams of ge-
ologists and surveyors scrambled over the land, documenting, measuring and sketching. It was excruciatingly time consuming, often taking many years just to collect the initial information. In the 1930s, the U.S. Geological Survey (USGS) started using aerial photography,
which significantly increased the accuracy and reduced the development time for new maps. For the first time, cartographers could truly get a birds-eye view of the landscape they were trying to draw. Today, the first step in topographic mapmaking is still the collection of aerial photographs
by either airplane or low-orbit satellites. The process requires meticulous planning. To get a stereoscopic or 3D image of land elevation, the land is photographed from two different, overlapping angles. The images are then scanned into a computer to extract the topography and convert it into contour lines. The development process for nautical charts is quite simi- lar, but rather than using aerial photography, the sea floor is mapped by ships equipped with specially designed SONAR. Field survey staff check accuracy by measuring the exact location of various control points
in the area of the new map. There are over 69,000 topographic maps covering North Ameri- ca that must be accurate to within 40 feet. With over 1000 charts covering over four million
22 ADVENTURE KAYAK | SUMMER/FALL 2013
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