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triangulation


dkruz

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I'm trying to create a cache where cache-seekers will need to do a little basic trigonometry to determine actual cache location. Not sure how to do this.

One possibility would be where seeker would be given gps coordinates of points A and B but needs to determine location of point C (actual cache location). Seeker could be given angles at points A and B and distance between all points. All seeker would need to do would be to do some basic trigonometry (with the angle and distances) and then use the GPS device to find the cache.

One thing I'm unsure of is how to use gps device to get the angle. This might be done through use of gps Heading. Not sure how to do this. On my Garmin GPS III plus I have choice of 4 different types of heading - auto mag var, true, grid and user mag var. These all seem to use actual or magnetic north as the basis for heading. How would one use these heading readings to derive angles for the 3 points of a triangle (where the 3 angles would equal 360 degrees)?

Any mathemeticians out there?

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I have done this with one of mine. I gave the compass bearings from A and B. Then the searcher just has to walk those lines to the point of intersection to search for C. This is pretty easy when you use your compass. You can use your GPS to check if you need to. If you can keep your angles fairly strong the intersection is fairly easy to see. JK

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quote:
Originally posted by dkruz:

I'm trying to create a cache where cache-seekers will need to do a little basic trigonometry to determine actual cache location. Not sure how to do this.

One possibility would be where seeker would be given gps coordinates of points A and B but needs to determine location of point C (actual cache location). Seeker could be given angles at points A and B and distance between all points. All seeker would need to do would be to do some basic trigonometry (with the angle and distances) and then use the GPS device to find the cache.

One thing I'm unsure of is how to use gps device to get the angle. This might be done through use of gps Heading. Not sure how to do this. On my Garmin GPS III plus I have choice of 4 different types of heading - auto mag var, true, grid and user mag var. These all seem to use actual or magnetic north as the basis for heading. How would one use these heading readings to derive angles for the 3 points of a triangle (where the 3 angles would equal 360 degrees)?

Any mathemeticians out there?


 

You might want to try just giving the distance to the cache and the waypoint of the next clue. The next clue would give the distance and the waypoint to the next clue. Once the finder has two distances ( and the distance between clues) then there are only two places on earth the cache could be. Given another clue, that narrows down the search to a single point.

 

If you give both an azimuth and distance, most GPS units can simply project a waypoint and the finder gets away without having to do any math.

 

When laying out your multicache you might want to use UTM and Grid North to make the math a little easier

 

... Two roads diverged in a wood, and I--

I took the one less traveled by, ...

 

unclerojelio[/url

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I have two caches that each require triangulation ...

 

One can be done using maps and compass

Do .. Not .. Seek .. The .. Treasure!

 

The other one requires mathmatical triangulation.

You Are The GPS!

 

A GPSr can only determine it's position. It may show you the bearing to a waypoint but this is not the same as an angle. If you provide two points and two distances, the cacher will need to determine which of two solutions is correct. You can solve that by giving him three reference points.

 

You'll find alot on this topic in this recent thread.

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There was a good one up here as well:

http://www.geocaching.com/seek/cache_details.asp?ID=16197

 

The coords were for the first cache which had cahce 2 AND the distance to the final (3rd) cache. The 2nd cache had only the distance to the final cache and you could use triangulation or intersecting circles to find it.

 

There is a link to a great how-to paper on the topic in the cache description.

 

BTW I used MS Streets & Trips and got within 13m of the final cache.

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It seems like there is a delicate balance to making a hard find and making an impossible find...a really difficult find I would assume brings a greater rush when you figure it out/find it- so I pose the question how hard is too hard? How involved should the pre-outting prep be? Could it be?

 

Just a thought...

 

QuiX

 

"We are the music makers, and we are the dreamers of dreams"

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quote:
Originally posted by QuixotiC:

It seems like there is a delicate balance to making a hard find and making an impossible find...a really difficult find I would assume brings a greater rush when you figure it out/find it- so I pose the question how hard is too hard? How involved should the pre-outting prep be? Could it be?

 

Just a thought...

 

QuiX

 

"We are the music makers, and we are the dreamers of dreams"


 

I ran into this problem when placing "Alluvial Material" with Team_epitome.

Click Here

 

We found that the trick is in giving the right clues. You can place a cache in the hardest possible spot to reach but if the clues are good, it may still be an easy find. The key is to not mislead or to have hunters looking somewhere they shouldnt. After we had placed this one, I was upset to hear people talking about disturbing the environment looking for it...when I thought about it, that was our fault for not being more clear about where, and where not to look.

 

Good luck placing a hard one..the real reward comes when the first find is posted...it makes it all worth it!

 

...and what is that quote from? I heard it in a song and am wondering what it is.

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"We are the music makers. We are the dreamers of the dreams."

–Gene Wilder as Willy Wonka,

quoting Arthur O'Shaughnessy

 

Most all of Wonka's quotes are from other people...

 

So you get half credit! icon_smile.gif

 

QuixotiC

 

Candy is dandy, but liquor is quicker...

 

"We are the music makers, and we are the dreamers of dreams"

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"We are the music makers. We are the dreamers of the dreams."

–Gene Wilder as Willy Wonka,

quoting Arthur O'Shaughnessy

 

Most all of Wonka's quotes are from other people...

 

So you get half credit! icon_smile.gif

 

QuixotiC

 

Candy is dandy, but liquor is quicker...

 

"We are the music makers, and we are the dreamers of dreams"

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