King Pellinore Posted February 12, 2003 Share Posted February 12, 2003 Given two points, or two sets of 'tudes, can you tell me how far apart they are? Is there an easy way of determining this? Or at least an equation? King Pellinore Quote Link to comment
BassoonPilot Posted February 12, 2003 Share Posted February 12, 2003 There probably is, but I cheat. If you have Microsoft Streets, you can "control-E" at one point and draw a line directly to another to find out how far apart they are. Quote Link to comment
hood Posted February 12, 2003 Share Posted February 12, 2003 dude, it's all about the pythagorean theorem, which states that in a right triangle, the length of the hypotenuse equals the square root of the sum of the squares of the two other sides. how does this apply to your question? let's say you have two points. first, take the horizontal components (the longitude values) and subtract the smaller from the bigger to get the difference. now do the same with the vertical components (latitude values). when you do that, you will have the horizonal distance between the two points, and the vertical distance between the two points. so, in a sense, we have two sides of a triangle. to obtain the third line of the triangle (the straight-line distance between the two points), just plug the two values we have into the pythagorean theorem like so: d = square root of ( (horizonatal dist)^2 + (vertical dist)^2 ) where d is the straight-line distance. Note: "^2" means "squared" hope this helps "Balance is for men who learn to know!" -Ween Quote Link to comment
+Ozarktroutbum Posted February 12, 2003 Share Posted February 12, 2003 Easygps, and best of all its FREE. When GPSr's are outlawed, only Outlaws will have GPSr's. Quote Link to comment
King Pellinore Posted February 12, 2003 Author Share Posted February 12, 2003 Hood, that's great! Especially if you're a member of the flat-earth society. Of course it would work for shorter distances? Ozark, what's easyGPS and how can I find out more? King Pellinore Quote Link to comment
+parkrrrr Posted February 12, 2003 Share Posted February 12, 2003 Everything you always wanted to know about great circles (and great circle distances) but were afraid to ask. Quote Link to comment
hood Posted February 12, 2003 Share Posted February 12, 2003 D'OH! D'OH! D'OH! D'OH!!!!!!!!! "Balance is for men who learn to know!" -Ween Quote Link to comment
+Choachy Posted February 12, 2003 Share Posted February 12, 2003 btw: Easy GPS If you enter them into your GPS(assuming your model has this feature), you can use the distance function on the map screen to select one point, and drag the cursor to the second point, and it will tell you the distance. My time, your time is limited, but time itself is unlimited. Quote Link to comment
+Web-ling Posted February 12, 2003 Share Posted February 12, 2003 OK, given two sets of coordinates, can anyone give me a formula to determine the BEARING from point A to point B? Yeah, I know I can use my GPSr, but I want to put it into my Access database. Quote Link to comment
King Pellinore Posted February 12, 2003 Author Share Posted February 12, 2003 thanks warm fuzzie, but that trig stuff is a smidge beyond my limited comprehension King Pellinore Quote Link to comment
+bitbrain Posted February 12, 2003 Share Posted February 12, 2003 You can download an app called Forward/Inverse (freeware) from Mentor Software. Given 2 sets of coordinates, the app will generate a distance and bearing. If you feed in one set of coords along with a distance & bearing, it'll generate the second set of coords. Very handy for planning multi-caches. Quote Link to comment
+bigredmed Posted February 12, 2003 Share Posted February 12, 2003 Topo maps are my thing. I have a map with lat/lon at the corners. I get a cache location that seems to be in the section of the map between the labeled corners, but I don't know how to place the spot on the map given the cache location and the coordinates of the reference corners. By appointment to the Court of HRM Queen Mikki I. Quote Link to comment
dsandbro Posted February 12, 2003 Share Posted February 12, 2003 In an Excel spreadsheet convert the x,y coordinates into polar coordinates using the ATAN function. Link the two. ======================================== Friends don't let Friends geocache drunk. Quote Link to comment
Lyra Posted February 12, 2003 Share Posted February 12, 2003 It's just a couple of miles. Always wear proper caching safety equipment! Quote Link to comment
+sbell111 Posted February 12, 2003 Share Posted February 12, 2003 If it were me, I would either use my GPS for this or use the pythag and ignore the fact that it isn't exact. Whenever I feel blue, I start breathing again. Quote Link to comment
+Markwell Posted February 12, 2003 Share Posted February 12, 2003 quote:Originally posted by Web-ling:OK, given two sets of coordinates, can anyone give me a formula to determine the BEARING from point A to point B? Yeah, I know I can use my GPSr, but I want to put it into my Access database. I've done it in Access, but it ain't pretty - and it's a work hog. BTW - the pythagorean works fine for short distances, but it assumes a flat earth. Webling, e-mail me and I'll give you the formulas. Markwell Chicago Geocaching Quote Link to comment
+ScottJ Posted February 12, 2003 Share Posted February 12, 2003 quote:how does this apply to your question? let's say you have two points. first, take the horizontal components (the longitude values) and subtract the smaller from the bigger to get the difference. now do the same with the vertical components (latitude values). This will work accurately only at the equator The reason is that 1 minute of latitude always equals 1 nautical mile, but 1 minute of LONGITUDE can be much LESS than 1 nautical mile ... it gets smaller as you move from the equator toward the poles. So, to find an accurate distance between any two points, we have to figure out the distance associated with a degree of longitude at the origin and destination points. For reasonable accuracy we can use the average of the two. -- Scott Johnson (ScottJ) Quote Link to comment
+evergreenhiker! Posted February 12, 2003 Share Posted February 12, 2003 If you wanted to avoid the math, you could use a map software program like TOPO!. Insert two waypoints and then draw a route between them...the program will tell you the distance between the points. Quote Link to comment
+mcdefjef Posted February 13, 2003 Share Posted February 13, 2003 this NOAA.gov website has a VBA-powered Excel spreadsheet and the VBA code that calculates all sorts of spherical geomoetry. Quote Link to comment
+majicman Posted February 13, 2003 Share Posted February 13, 2003 But what if you are a Christian and don't believe in pythagoras? --majicman My new book available now!: (http://www.mcwj.com ) Quote Link to comment
+Web-ling Posted February 14, 2003 Share Posted February 14, 2003 quote:Originally posted by Markwell: quote:Originally posted by Web-ling:OK, given two sets of coordinates, can anyone give me a formula to determine the BEARING from point A to point B? Webling, e-mail me and I'll give you the formulas. Thanks, Markwell! Got your email, and have more or less incorporated it into my database. The web page mcdefjef referenced was very helpful, too. Quote Link to comment
+Freelens&Mosie Posted February 14, 2003 Share Posted February 14, 2003 callup someone close and say "Hey how far is it to X"? I'm just lazy I guess. I have my own little world. But it's OK...they know me here. Quote Link to comment
MTU_Cache_Spot Posted February 14, 2003 Share Posted February 14, 2003 NGS Geodetic Toolkit There's a little bit of surveyor mumbo-jumbo, but it's not too hard to figure out... I believe that the program you're looking for would be INVERSE (or INVERSE3D if you're interested in elevation difference as well) Quote Link to comment
+writer Posted February 14, 2003 Share Posted February 14, 2003 If the points are in the same general area, it's easy. Switch to UTM coordinates, which present locations as linear offsets from specific reference points. You can find the difference between the northing and easting coordinates, which gives you two legs of a right triangle, then use the Pythagorean theorem as someone suggested. If you are uncomfortable with metric measures, just convert after you are done. (The measurements, that is, and not your personal belief system.) If the points are close but on either side of a UTM zone division, check maps to find the eastings of the borders, and that should let you determine the difference. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.