Averaging Coords

[+matfam]

Does anyone know how to average any set of coords. I don't believe that it can be does by adding the numbers and then dividing by the total number of coords, because all of the numbers are not Base 10.

[+JohnnyVegas]

Does anyone know how to average any set of coords. I don't believe that it can be does by adding the numbers and then dividing by the total number of coords, because all of the numbers are not Base 10.

If you have a magellan then your GPS does it for you. I am not a big fan of cachers doing their own averaging. Every time I have found a cache in which the cache owner states he took several readings and averged them out I have found the coordinates to be some of the worst I have ever had to deal with.

 

What helps also is haveing your GPS turned on for a least 15 minutes before you take a reading. then take one reading and be done with it. You are not going to get much better than 10-20 feet in accuracy with any consumer grade GPS.

[+matfam]

Thanks but not the info I'm looking for. I would like to know how to average several sets of coords that are miles apart.

[+fizzymagic]

Thanks but not the info I'm looking for. I would like to know how to average several sets of coords that are miles apart.

Then you need to define what you mean by "average," because that is not at all well-defined for coords that far apart.

 

Do you mean that you are trying to find a point that is the same distance from each of three other points, for example?

[+Rotareneg]

You can just convert the coordinates to decimal degrees and then calculate the arithmetic mean in the normal manner, if that's what you're looking for.

Edited January 14, 2006 by Rotareneg

[+Prime Suspect]

Does anyone know how to average any set of coords. I don't believe that it can be does by adding the numbers and then dividing by the total number of coords, because all of the numbers are not Base 10.

Just convert all the numbers to a common base, and then do the math. I'd suggest base 10, unless you're from the planet Xorglon, in which case you're more familiar with base 37.

[+matfam]

Thanks but not the info I'm looking for. I would like to know how to average several sets of coords that are miles apart.

Then you need to define what you mean by "average," because that is not at all well-defined for coords that far apart.

 

Do you mean that you are trying to find a point that is the same distance from each of three other points, for example?

Exactly...Now how do I do that

[+Freebee & 007]

Thot's Free geocaching utilities.

Download :Here

 

There is a combo pack that includes a Coord averaging application.

At least I think this is what you are looking for??

[+CharlieP]

In the field, one way to find the point equidistant from three given points is (1) by trial and error using the Measure Distance function on the map page of the GPS (if your GPS has this) or (2) by getting in the right general area with your GPS and moving around until the distance to each of the three points is equal. From home, you could (3) solve it graphically using either pencil and paper or (4) a map program such as Street Atlas, or (5) by trial and error using a tool such as the U.S. Coast Guard's Posaid which can give distances between points. The scientific way would be (6) by using a mathematical equation, which would probably work best with UTM coords.

 

Unless you are good with numbers or have a map program, methods (1) or (2) are probably your best bet.

Edited January 16, 2006 by CharlieP

[+JDandDD]

Rather than doing it mathematically I do it graphically as suggested. For instance, when I'm putting out a cache I usually take 4 to 8 readings on several days, then plot them on a map and take a point that is roughly in the middle. Usually works well except when the readings are under trees or other area that throws the readings way off from each other.

 

JDandDD

[+Renegade Knight]

Thanks but not the info I'm looking for. I would like to know how to average several sets of coords that are miles apart.

Then you need to define what you mean by "average," because that is not at all well-defined for coords that far apart.

 

Do you mean that you are trying to find a point that is the same distance from each of three other points, for example?

Exactly...Now how do I do that

I can't spell it but if you can draw it on a map you can use that map to lay out the problem and solve it using Pythragriams Theorem.

 

Here is a script found using "Solving Triangles" mostly because I can't spell the right theorem.

http://www.hostsrv.com/webmaa/app1/MSPScri...veTriangles.jsp

 

Use your GPS to convert your coordinates to UTM. UTM makes the math much easier.

 

The theorem

http://www.cut-the-knot.org/pythagoras/index.shtml

Edited January 16, 2006 by Renegade Knight

[+Team Cotati]

Does anyone know how to average any set of coords. I don't believe that it can be does by adding the numbers and then dividing by the total number of coords, because all of the numbers are not Base 10.

If you have a magellan then your GPS does it for you. I am not a big fan of cachers doing their own averaging. Every time I have found a cache in which the cache owner states he took several readings and averged them out I have found the coordinates to be some of the worst I have ever had to deal with.

 

What helps also is haveing your GPS turned on for a least 15 minutes before you take a reading. then take one reading and be done with it. You are not going to get much better than 10-20 feet in accuracy with any consumer grade GPS.

Geez Johnny, aren't you afraid of making things too simple? Thank you. I do the same but I do take a second reading for good measure.

[+Thot]

Thanks but not the info I'm looking for. I would like to know how to average several sets of coords that are miles apart.

Depending on how accurate you need to be and how far apart the coordinates are this can be a complicated problem. If you are only a mile or so apart and you can tolerate an error of a foot or so then you can do what a couple of people suggested. Convert the coordinates to whole degrees and average them.

 

As somebody said, my coordinate averaging utility will do this using linear arithmetic http://factsfacts.com/geocachingsoft/Avera...Coordinates.htm

 

But distances on a sphere are not linear. The earth is not a perfect sphere. The farther you are from the equator the smaller a degree of longitude is.

Edited January 16, 2006 by Thot