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elevation


YF Tony & Laura

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Hi, I just got an eTrex Venture and have been finding caches for a few weeks now. This is fun!

 

When I'm looking at the cache descriptions online, I see the coordinates, but no elevation. It seems like I might get a more accurate reading when caching if I also had the elevation stored in my GPS unit. Do you all just punch in (or download) the coordinates and go?

 

I havent successfully hooked my GPS to the PC yet. Maybe the elevation is included in the downloadable info?

 

I guess as I approach the cache, I could adjust the elevation based on current readings. My own post has started me thinking...

 

Thanks, Tony

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The elevation capabilities on the lower end units like most of us use for Geocaching doesn't do so well with elevation. In most cases, my elevation is reasonably close but I've seen it several hundred feet off when it's showing 20 foot accuracy, in addition to it's normal range of inaccuracy.

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I have a Magellan SporTrak Pro. When I have it go to a waypoint, it's assumption is that the point is at the elevation marked on the Topo maps I've downloaded into it.

 

So, let's say that I am at 100 feet and the waypoint (the assumed location of the cache) is at a point that the topo map thinks is at 200 feet. I guess you could say that the GPS is "assuming" that the cache is at an elevation of 200 feet.

 

But that doesn't necessarily mean that the cache really is at exactly 200 feet. It could be in an indentation, down a hole, in a tree, etc.

 

All of that said, I have found it of no use at all to worry about the altitude of the cache. I simply follow the arrow, and when I get to the waypoint, I search for the cache.

 

What the Topo maps do for me is to give me details of terrain that make it easier to navigate to the cache. If there is going to be a significant gain in elevation searching for the cache, I assume that the cache owner will mention it in the cache description.

 

Shannah

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The only time I have found that the elevation could be good to know, is if the cache is hidden on a very steep slope. Moving 10-15 meters to the side, may make a significant difference in altitude on such a location. I've found a cache in France, where I at first was, as it seemed, exactly at the location. No cache there, but after a little while I understood that the cache was at the bottom of a man-made object, and I was standing at the top of it. The building was built on a slope, so depending on from which direction you entered, you either came to the top or to the bottom.

 

So, several meters from the cache, yet at exactly the correct position. On the other hand, the GPS altimeter function may not have been accurate enough to tell me where to go at that time, had I known the altitude in advance.

 

Anders

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I'm a newbie, but adjusting the elevation on my two finds today seems to have made a difference. When I manually entered the coords on my eTrex, for whatever reason the "default" elevation was 79 ft. below sea level. When I got close to each cache, I noted my actual elevation (+59 and +53 feet), edited the waypoint, and hit GoTo again. In both cases, I got much closer than I had with my previous two finds where I didn't use the elevation -- in fact, I didn't need the hints. It seems to me that if I hadn't changed the elevation on the waypoint, I would have been ~120 feet off. Of course, this is assuming the coords for the cache are accurate.

Am I not understanding the third dimension of this? icon_confused.gif It seems to me if I was standing on the edge of a cliff 200 ft above sea level, directly over a cache hidden in the face of the cliff 100 ft below me, the GPSr would say I'm 100 ft away. I guess the arrow would spin as I moved because it wouldn't be N, S, E or W of me, but...

I understand what Kerry and Team Dragon say about the accuracy of elevation on entry-level GPSrs, but it seems to have made a difference today. Or maybe it's just that the cachers' coordinates were more accurate.

 

No matter how cynical you become, it's never enough to keep up. - Lily Tomlin

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I'm a newbie, but adjusting the elevation on my two finds today seems to have made a difference. When I manually entered the coords on my eTrex, for whatever reason the "default" elevation was 79 ft. below sea level. When I got close to each cache, I noted my actual elevation (+59 and +53 feet), edited the waypoint, and hit GoTo again. In both cases, I got much closer than I had with my previous two finds where I didn't use the elevation -- in fact, I didn't need the hints. It seems to me that if I hadn't changed the elevation on the waypoint, I would have been ~120 feet off. Of course, this is assuming the coords for the cache are accurate.

Am I not understanding the third dimension of this? icon_confused.gif It seems to me if I was standing on the edge of a cliff 200 ft above sea level, directly over a cache hidden in the face of the cliff 100 ft below me, the GPSr would say I'm 100 ft away. I guess the arrow would spin as I moved because it wouldn't be N, S, E or W of me, but...

I understand what Kerry and Team Dragon say about the accuracy of elevation on entry-level GPSrs, but it seems to have made a difference today. Or maybe it's just that the cachers' coordinates were more accurate.

 

No matter how cynical you become, it's never enough to keep up. - Lily Tomlin

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I have two urban caches that involve urban bridges. The caches are each on the lower (less busy) street, just out from under the bridges themselves. So the margin of error on your GPS includes some of the higher street.

 

(Let me clarify, before we get into the "caches by bridge supports make people nervous" conversation, that one of the caches is a micro and the other is virtual)

 

Giving altitude information, even if it were accurate, would spoil the fun!

 

evilrooster

-the email of the species is deadlier than the mail-

 

[This message was edited by evilrooster on July 28, 2002 at 11:21 PM.]

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ok, so if the default is -79 and the ground level is +58, i dont see where altitude makes a difference.. you entered the elevation, but since that is an UP down where as the coords are right,left, forward, back thing, i dont see how it could help unless you were actually thinking of digging for it. personaly i have never messed w/ the elevation feature. and though im sure there is a reason for it, i can not concieve of any possible use i would have for it. (now here come the hypothetical suggestions im sure) as i said any use I would have for it. others may use it moderately to often, i never have.

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Setting the elevation has no effect on the accuracy of the coordinates, you could be 10,000 feet up in helicopter and your GPSr could read 10 feet from the cache. Elevation is however a 3rd dimension, so if you had that info and the GPS reading was anywhere near accurate, it would would make it easier to find the cache. Not sure as I would want that information though.

 

Ironically, I went deep sea fishing this weekend and took my GPSr for fun, for a while elevation was -10 feet!

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