Baron Carter wrote: > On 1:50 000 topo maps I have seen in other countries the contours > were at 20 > m. Usually there are supplementary contours at 10 m intervals in areas of > very low relief and where the standard contours are spaced more than 25 mm > apart. > > I do not believe that this was some arbitrary decision by USCG. There's > bound to be a standard. > Baron, I'm sure it was thought through carefully, and not just chose arbitrarily. John, Paul, I understand the article was more critical of the actual spacing than SI. But there were a lot of indirect swipes at SI, lumping it with "technocrats", "hairbrained flatlanders", "the metric system might have worked" (as if it doesn't), etc. I tend to be dismissive of articles with that sort of tone. Nevertheless it's interesting to see USGS putting out topo graphs in SI! Nat http://www.win.net/dorsea/nehager > Baron Carter > > -----Original Message----- > From: Nat Hager III [mailto:[EMAIL PROTECTED]] > Sent: Friday, 27 July, 2001 14:33 > To: U.S. Metric Association > Subject: [USMA:14661] Denver Post > > > Now don't everyone get mad at once. Remember, it's just someone who went > into journalism, because he/she couldn't pass basic math/science. > > The important thing is just to monitor, and make sure articles like this > aren't having significant influence on public thinking. > > Nat > > ------------------------------------------- > > Copyright 2001 The Denver Post Corporation > The Denver Post > > > July 24, 2001 Tuesday 2D EDITION > > SECTION: DENVER & THE WEST; Pg. B-09 > > LENGTH: 870 words > > HEADLINE: Another mapmaking revolution > > BYLINE: By Penelope Purdy, > > BODY: > The U.S. Geological Survey, purveyor of America's definitive maps, has > spent your tax money on a new system that makes the most used detailed > terrain maps, called topos, less useful. > > Few items are more essential to a backcountry traveler than accurate > topological maps. They not only show roads and trails, they use > colors and > contour lines to depict steep hillsides, deep canyons, rugged peaks and > impassable bogs. > > Even in the age of Global Positioning Systems, a topo remains uniquely > suited for specific tasks. It is the end product of centuries of human > attempts to show the world in a useful way, as much a statement about our > civilization as it is of the physical world. > > The most detailed topos used by the general public are 7.5 minute > quadrangles. In the past, the 'seven-and-half quads' showed terrain in > 40-foot intervals, so if there was a 50-foot cliff in the way, you could > avoid it. > > Now the USGS has embraced a 20-meter contour interval. The metric system > might have worked - if the bureaucrats had chosen a reasonable vertical > distance. > > But 20 meters translates into about 66 feet, a vertical distance that can > hide an annoyingly large number of cliffs and other obstacles. > > The upshot: The 21st century maps being created by the USGS are > less useful > than those it produced the 1960s. > > Surely the 20-meter standard was the harebrained creation of some > flatlander who has never stumbled through the chaos of a mountain boulder > field. > > A friend and I discovered the new maps' shortcomings traipsing around > California's Sierra Nevada. The particular climbing route was fairly > straightforward. The problem was finding the (expletive) thing. > We spent a > quarter of an entire day stumbling through the talus at the peak's base > because our map's 20-meter interval lead us into several 40-foot > drop-offs. > > People who love electronic toys may smirk that, well, we > should've just had > ourselves a GPS unit. But GPS has many shortcomings. Batteries fail, > signals die in thick forest cover or among deep cliffs, and even the new > gizmos are heavy and bulky compared to a map and compass. > > Worse, a GPS makes a person focus on the gadget rather than the world > around them. I've been stopped on the trail by GPS users who asked to see > my paper map. I even witnessed hikers stand around and argue about where > they needed to go, when the path they sought was a few yards in front of > their noses. > > Now, consider this: While returning from the California climb, > my buddy and > I hiked out by a crescent moon's faint light. Given the awful time we had > finding the climbing route, we wanted to reach camp by a route different > from the one we'd taken earlier - a tricky problem for GPS, which records > only known data points. > > But because I'd been glancing at a topo all day, I had in my > head a pretty > good notion of the terrain that lay to either side of our original path. > Thus, we could walk without using our headlamps. Often in the > backcountry, > you don't want to use your lights because they destroy your > night vision so > all you can see is that small circle of light. And staring at the > illuminated screen of a GPS causes the same problem. > > Trouble was, of course, that the mental picture I had was based on the > USGS' new 20-meter interval, so we still encountered several > drop-offs - a > problem euphemistically called getting 'cliffed-out.' > > You can sympathize with the mapmakers' dilemma: They need to depict a > spherical world on a flat surface, so there's always some > distortion - it's > like trying to detail a basketball on a postage stamp. But if mapmakers > pick the wrong mathematical formula, or projection, the map ends up > unsuitable for broader use. That's basically what's happened to > USGS quads. > > That's also what happened to a dude named Gerardus Mercator who > invented a > decent map for navigating oceans in the mid-latitudes. His projection was > part of the massive 16th century revolution in cartography, which erupted > as knowledge of the Western Hemisphere reached the emerging scientific > caste in Europe and forever changed how humans envision their world. > > Trouble was, people misused Mercator's map to form government > policy, too. > And since Mercator's projection showed Europe disproportionately > large and > minimized Africa and other southern locales, it skewed the world view > widely held by generations of politicians and school kids. It > was a classic > case of misunderstanding the product of technology - for maps are as much > about politics as geography. > > Today, satellites and computers are fomenting another mapmaking > revolution, > the likes of which civilization hasn't seen since Mercator's > era. Maps are, > in a sense, the very foundation upon which our society has been built and > continues to evolve. > > But like politics, sometimes technology embraces silly notions. And the > 20-meter interval is a classic case of a technocrat's convenience > overriding the needs of the on-the-ground user. > > Penelope Purdy ([EMAIL PROTECTED]) is a member of The Denver Post > editorial board. > > >
