triangulation caches

[+tide28]

Is there an easy way to figure these out. A phone app? I'm not a math person.

[+edscott]

Not sure how yours is set up. The only one I ever tried was solvable by using a map and a drawing compass.

[+narcissa]

There's no "easy" way. There are apps that will help you with the math, but you still need to understand which values to plug into the formula.

[+unabowler]

One of my hides is a triangulation cache. I should say it's actually a trilateration cache because the cache is a given distance from each of three other caches. I'm a math person so I'd say it can be easily found using the formulas, but most finders have just used their GPS receivers to home in on it using the other nearby caches.

[+tide28]

Thanks everyone. Since I'm new at this I guess I better wait til I get a gps...using my phone gps right now. And find someone really smart at math. I'll just have to do the easy ones right now til I get better at this. Got a lot to learn but it was fun finding the ones I've found so far.

[+The Jester]

Some of the computer map programs can help out. I've use MS Streets & Trips for many of these types of caches.

[+PeoriaBill]

Some of the computer map programs can help out. I've use MS Streets & Trips for many of these types of caches.

 

You might try Apps like: IGCT Pro or GCTools which will work on your iPhone.

 

GSAK can also be used, if you are working with a laptop/pc. Do two simple projections, plot both coords, then draw lines on your mapping program and the intersection is your cache location.

 

Your GPS will also allow you to do projections to get both sets of projected coords. These can be plotted on a map.

 

Hope this helps. I am sure there are other techniques/methods to use, but these the ones that came to mind for me.

[+GeoTrekker26]

Some of the computer map programs can help out. I've use MS Streets & Trips for many of these types of caches.

 

You might try Apps like: IGCT Pro or GCTools which will work on your iPhone.

 

GSAK can also be used, if you are working with a laptop/pc. Do two simple projections, plot both coords, then draw lines on your mapping program and the intersection is your cache location.

 

Your GPS will also allow you to do projections to get both sets of projected coords. These can be plotted on a map.

 

Hope this helps. I am sure there are other techniques/methods to use, but these the ones that came to mind for me.

 

I don't understand your method to solve it. Here is a sample from an archived cache:

 

Poplar Hill ( N 42 28.116 , W 71 20.767 )

599 meters from here

 

St. Bernard’s Cemetery ( N 42 27.948 , W 71 19.951 )

698 meters from here

 

Concord Monument ( N 42 27.660 , W 71 20.953 )

806 meters from here

 

I don't see how projecting two lines will solve it.

[+fizzymagic]

I don't understand your method to solve it. Here is a sample from an archived cache:

 

Poplar Hill ( N 42 28.116 , W 71 20.767 )

599 meters from here

 

St. Bernard’s Cemetery ( N 42 27.948 , W 71 19.951 )

698 meters from here

 

Concord Monument ( N 42 27.660 , W 71 20.953 )

806 meters from here

 

I don't see how projecting two lines will solve it.

 

It won't.

 

There are a few different ways to solve these problems. You can use UTM, which works remarkably well for trilateration. I have a file explaining it here.

 

You can also do it by going into the field with your GPS and moving until the distances are all correct. That can get tedious.

 

I wrote myself an exact solver (which includes the curvature of the Earth and everything) but that's my own little secret!

[+niraD]

There are a few different ways to solve these problems. You can use UTM, which works remarkably well for trilateration. I have a file explaining it here.

 

You can also do it by going into the field with your GPS and moving until the distances are all correct. That can get tedious.

 

I wrote myself an exact solver (which includes the curvature of the Earth and everything) but that's my own little secret!

And of course, there's also the brute force approach that I've used.

 

I started by eyeballing a map to guess a general area where I thought the cache would be. Then I opened an online distance calculator in three separate browser tabs, and then entered the three reference points, one in each tab. Then I entered the coordinates of my guess in each of the three tabs and submitted the forms.

 

Naturally, the distances were off, so I adjusted my guess, entered it into all three tabs again, and repeated. Eventually the error was within the EPE of a typical consumer GPSr, so I went and found the cache.

[+redsox_mark]

Given 3 points with distances, I've simply drawn 3 circles on Google Earth, and looked where they intersect. That got me close enough.

[+rjb43nh]

Given 3 points with distances, I've simply drawn 3 circles on Google Earth, and looked where they intersect. That got me close enough.

 

That's the quickest way. I used TopoUSA the other day and the intersection of the 3 circles, while not exact, should get you within about 3 meters. This method works best over relatively short distances.

[+J Grouchy]

You can try this site: http://www.geocachingtoolbox.com/index.php?lang=en&page=circleIntersection&status=result

 

You can add circles...though the more you add, the less chance of them truly intersecting at a single point. I have one near me that uses four reference points and the result is a triangular area approximately 170 square meters in a densely wooded area.

[+unabowler]

There are a few different ways to solve these problems. You can use UTM, which works remarkably well for trilateration. I have a file explaining it here.

 

You can also do it by going into the field with your GPS and moving until the distances are all correct. That can get tedious.

 

I wrote myself an exact solver (which includes the curvature of the Earth and everything) but that's my own little secret!

And of course, there's also the brute force approach that I've used.

 

I started by eyeballing a map to guess a general area where I thought the cache would be. Then I opened an online distance calculator in three separate browser tabs, and then entered the three reference points, one in each tab. Then I entered the coordinates of my guess in each of the three tabs and submitted the forms.

 

Naturally, the distances were off, so I adjusted my guess, entered it into all three tabs again, and repeated. Eventually the error was within the EPE of a typical consumer GPSr, so I went and found the cache.

 

My method works just like that except I use MS Excel. For each of the three points, I have a cell containing the distance from my target point, and then another cell for the sum of the three distances. I use the solver to set the sum cell equal to zero by changing the target point, and the resulting target point is the cache location.

[+PeoriaBill]

Sorry, from you comments I understand you are looking for the intersection of three circles. The two iPhone apps I mentioned will work. If you have a program like MS Streets and Trips you can draw three circles and the intersection is your cache. Again there are other methods/techniques that will work. best regards.

[+The Jester]

Some GPSr's allow you to set proximity alarms at user selected distances. The ones I've seen then draw a circle on the map page, so the intersection would be the cache.

[+Triskelle]

Try this - Dutch - site for a wide variety of calculations with coordinates.

Edited February 14, 2015 by Triskelle

[+GeoTrekker26]

Try this - Dutch - site for a wide variety of calculations with coordinates.

 

A very handy site, thanks!