+geokesh Posted June 9, 2009 Posted June 9, 2009 Hi, I'm fairly new at this, and I've noticed some of the mystery caches tell you to assume "the world is round" or to assume "the world is flat". What does this mean in terms of solving the puzzle or projecting waypoints? Thanks. Quote
+briansnat Posted June 9, 2009 Posted June 9, 2009 It may have something to do with map projections. Beyond that I have no idea. Quote
+Arrow42 Posted June 9, 2009 Posted June 9, 2009 Hi, I'm fairly new at this, and I've noticed some of the mystery caches tell you to assume "the world is round" or to assume "the world is flat". What does this mean in terms of solving the puzzle or projecting waypoints? Thanks. I don't know about those specific caches, so my information might not relate. Since the world is round representing the map as flat distorts distances between two points. It can also change where two line intersect. For example, if you are given 4 location and asked to draw an X between them, you would get two different locations depending if you are looking at a globe or looking at a flat map. Quote
+geokesh Posted June 9, 2009 Author Posted June 9, 2009 Does anyone know if there is a setting on the GPSr that compensates for these assumptions? Quote
savant9 Posted June 9, 2009 Posted June 9, 2009 My thought is that they are mentioning this to simplify things. The world is far from round, and even lakes aren't flat.... Quote
+WRASTRO Posted June 9, 2009 Posted June 9, 2009 Can you give some examples of the caches that are using this verbiage? Seeing it context will help in coming up with reasonable responses. We aren't going to be solving any puzzles for you but we can at least help you interpret what you are reading. Maybe... Quote
+TerraTrekkers Posted June 9, 2009 Posted June 9, 2009 Archived example Vincenty's Dilemma, Jim Quote
+WRASTRO Posted June 9, 2009 Posted June 9, 2009 Archived example Vincenty's Dilemma, Jim Yep, math and geometry can be great fun. Good example. To the OP: what examples do you have? Quote
+geokesh Posted June 9, 2009 Author Posted June 9, 2009 This is the cache that first got me all confused: TESTING TO DESTRUCTION http://www.geocaching.com/seek/cache_detai...ae-3f2fe43e8cd2 Quote
+Renegade Knight Posted June 9, 2009 Posted June 9, 2009 Does anyone know if there is a setting on the GPSr that compensates for these assumptions? UTM coords assume the world is flat. This is why you have UTM regions (or whatever they call them). WGS84 assumes the world is round(ish). No regions. Quote
+Chrysalides Posted June 9, 2009 Posted June 9, 2009 OMG the world is ROUND???? No no.. assume the world is round. Any right thinking person knows that the world is pretzel-shaped. That's why many things are so twisted. Quote
+geokesh Posted June 11, 2009 Author Posted June 11, 2009 Thanks for the help. I always wondered why the world smelled constantly of pretzels. Quote
+Curioddity Posted June 12, 2009 Posted June 12, 2009 OMG the world is ROUND???? I take great comfort in this epiphany! I finally understand why I couldn't find a single edge. Pete Quote
+fizzymagic Posted June 12, 2009 Posted June 12, 2009 (edited) This is the cache that first got me all confused: TESTING TO DESTRUCTION http://www.geocaching.com/seek/cache_detai...ae-3f2fe43e8cd2 It's meant to take a plane geometry problem and cast it as a real-world problem without the added complexity. Unfortunately, it introduces some ambiguity into the puzzle. Which north are you supposed to use for the (very precise) azimuth? Magnetic north? That doesn't make sense, as the declination is only precise to about a half degree, so the bearings cannot be measured from magnetic north to that precision. Grid north? No, he mentions declination. Should you accommodate for the grid skew in the calculations or not? Probably, given the attempt to fit the plane-geometry problem into the plane, the author means to use whatever declination is published (to the nearest half degree) , to treat it as infinitely precise, and to assume that grid north does not change over the scale of the problem. I guess I am not overly impressed by the puzzle. The fact that the world is (mostly) round makes these problems a lot more difficult, even when the cache owner tries to remove it! Edited June 12, 2009 by fizzymagic Quote
knowschad Posted June 12, 2009 Posted June 12, 2009 OMG the world is ROUND???? No no.. assume the world is round. Any right thinking person knows that the world is pretzel-shaped. That's why many things are so twisted. And geocachers are the salt of the Earth. Quote
CacheNCarryMA Posted June 12, 2009 Posted June 12, 2009 (edited) If you're assuming the world is round, you also need to make assumptions about which side of the curve we live on. I remember reading something about folks who postulated that the world is round, but we live on the inside of a hollow sphere -- like inside a giant Kinder Egg. Edited June 12, 2009 by CacheNCarryMA Quote
+flask Posted June 13, 2009 Posted June 13, 2009 I always wondered why the world smelled constantly of pretzels. i thought that was just my bedroom. Quote
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