Gps Elevation Question

[+ComputerSnack]

I'm new to geocaching, and was wondering about elevation. I notice that it it not mentioned as part of the coordinates. When I enter the coordinated into my GPS, I've just been leaving the elevation as what it is. Does it matter?

[+Team Cotati]

I'm new to geocaching, and was wondering about elevation. I notice that it it not mentioned as part of the coordinates. When I enter the coordinated into my GPS, I've just been leaving the elevation as what it is. Does it matter?

Most GPSr's will calculate the elevation of where you are located with 3 or 4 satellites available. Why would you want to enter the elevation even if you could? When you say that you are leaving the elevation as what it is....what elevation are you referring to?

Edited March 6, 2005 by Team cotati697

[+Cardinal Red]

kpraeger Posted on Mar 6 2005, 05:55 PM

When I enter the coordinated into my GPS, I've just been leaving the elevation as what it is. Does it matter?

 

No, If you are only searching for a Cache, Elevation is irrelevant to actually verify you are at a specific Location. When I save a Cache Location (and have no idea what the Elevation is) I Zero it out.

 

If you save an actual Waypoint, it's nice that the Elevation is saved along with the Location.

[StanB]

In my opinion elevation is unimportant. About the only time I'd look at elevation would be with a high difficulty cache where I'd check a topo map to determine if I have to scale a mountain or high ridge. But GPS elevation is somewhat inacurate and a barometric altimeter requires accurate calibration each time you use it.

[+Cardinal Red]

Team cotati697 Posted on Mar 6 2005, 06:13 PM

When you say that you are leaving the elevation as what it is....what elevation are you referring to?

 

On many GPSr devices you can NOT enter a brand new Waypoint from scratch.

 

You can MARK your current Location (complete with Elevation) and edit it as required before saving. I zero out that Elevation number only to avoid confusion. The GPSr does not use this information to find a Waypoint.

[+reveritt]

I do excatly what you do--just ignore the elevation when entering a waypoint.

[+IVxIV]

..On many GPSr devices you can NOT enter a brand new Waypoint from scratch.

 

Sorry but,, I think on most EVERY GPS made you actually CAN enter a "waypoint from scratch".. Before leaving the house I pre-load the coordinates of the first cache I plan to find, then let the GPSr guide me to the spot, Or am I missing your point?

[+WeightMan]

I had one cache I found where the elevation was important to the find. It was on the top floor of a parking garage and the elevation is the only way to know that. The first try for it was at street level.

 

The basic problem with using elevation is that the GPSr is less accurate in elevation that in location. I was walking along a trail next to a river the other day and the GPSr was showing elevations of 30-40 feet below sea level. Since I was a good 40 feet above the river and the river is not tidal at that point, the GPSr was at least 75-80 feet off in elevation. The EPE reported by the unit was less than 20 feet.

[+º]

Or am I missing your point?

Yes, e.g. if you use the etrex yellow without a pc you have to mark a new waypoint. The etrex will use the coords and elevation of the point where you are or of the last know position.

If you have a etrex yellow you can not enter a brand new Waypoint from scratch without a pc.

[+JohnnyVegas]

But GPS elevation is somewhat inacurate and a barometric altimeter requires accurate calibration each time you use it.

It depends on the GPS, some have bormetric altimeters in them.

I have Suunto watch with a Barometric altimeter that I use. When I check my Maridain gold next to my Suunto they are alway a few feet within each other in altitude. Now even a barometric altimeter can be off and the should be reset

and a known elevation before they are used.

[+IVxIV]

Or am I missing your point?

..If you have a etrex yellow you can not enter a brand new Waypoint from scratch without a pc.

You're kidding?!?

 

You mean if I had an Etrex Yellow GPSr, and while at a friends house my buddy wants to give me coordinates of a good fishing spot he found, I couldn't key them into the unit there and go to the fishing spot?? All my prior GPSr's (Magellan 4000XL, Magellan 315, Lowrance iFinder) could do that no problem..

[+Cardinal Red]

IVxIV Posted on Mar 7 2005, 09:06 AM

I couldn't key them into the unit there and go to the fishing spot??

 

Yes you can. But when you say "key them into the unit", that's where we have to clarify. Just exactly like teamguzbach.org said "The etrex will use the coords and elevation of the point where you are or of the last know position."

 

So if you were at N 75 Deg 12.345 Minutes and W 41 Deg 34.567 Minutes and the Elevation at that point was 500 Feet, that would be your starting point. You would have to EDIT all that information to to Fishing Spot your buddy told you about.

 

And if you knew the Fishing Spot Elevation was at 250 Feet, you could change the 500' to 250'. Or if you didn't know the Elevation you could either ZERO it out, or leave it at the incorrect 500'.

 

It would NOT make any difference in finding the Fishing Spot, but I would not SAVE an incorrect Elevation after my EDITS were complete. I would ZERO it out just because it would bother me otherwise.

 

Now. How about if you explain the procedure you use to enter a Brand New Waypoint. I have never owned the type you must have.

[+Poindexter]

It's the same thing, just a different way of looking at it. I mark my present location and then edit it to the location that I really want entered. How is that any different than just entering a waypoint from scratch? You still have to enter the numbers.

[jwillis]

I too agree that having the elevation would be a nice help. We did one that was on the side of a cliff and were scratching our heads over it.

[+Cardinal Red]

kpraeger Posted: Mar 6 2005, 05:55 PM

When I enter the coordinated into my GPS, I've just been leaving the elevation as what it is. Does it matter?

 

Yes there are going to be Caches that have been cleverly hidden, and the elevation can be an important factor to locate it.

 

But if you actually read the ORIGINAL post. "I've just been leaving the elevation as what it is".

 

I don't know any other way to interpret this except:

 

1> The actual Elevation at the remote location has not been explicitly provided.

 

2> The Waypoint he wants to MARK / ENTER / EDIT / SAVE is either going to be a ZERO or some number that is NOT the actual Elevation.

 

If the question had been "If I know the Elevation, should I bother entering it?" Well yes, and here are 20 reasons why ..............

 

But as I read it the question boils down to "I don't know the actual Elevation of this Waypoint. But there is some type of incorrect information in the Elevation Display. Will I have a problem going to this Lat / Lon Coordinate if I have ZERO ELEVATION or the WRONG ELEVATION saved with the Waypoint. No. End of story.

[+mzmtg]

Why is my elevation, as inidcated on the GPSr, constanly changing when I'm not moving?

[+WeightMan]

Why is my elevation, as inidcated on the GPSr, constanly changing when I'm not moving?

Assming you don't have a barometric sensor, the GPSr is constantly updating information from the satellites. As it does so it recalculates your position. You may also notice that the distance to the cache changes as well for the same reason. Since the elevation calculations requre more satellites, they will change more often.

 

By the way for barometric units, do you have to reset the barometric setting? The sensor reads the current barometric pressure and is only as accurate as the current sea level barometric pressure. As that changes with weather, the unit needs to be reset or it will not be accurate.

[+Cardinal Red]

WeightMan Posted on Mar 9 2005, 04:23 PM

By the way for barometric units, do you have to reset the barometric setting?

 

On my GPS Map76S, you can set the Barometer, but you don't have to. You can choose to Enter a "known good pressure or exact elevation" (out of the Garmin Manual). For best accuracy this would be "preferable". But who has that data handy when you need it. I just set it to allow "GPS Calibration". That setting combines Satellite Data and the Barametric Sensor to determine the best possible solution (in the absence of the precise Calibration Data mentioned previously).

 

But it takes a while "Calibration is applied slowly except when the unit is first turned on". The Altitude jumps around at first. Then it seems to settle down somewhat. But early on, even when the Altitude seems to be stabilized, the number on the Display is NOT the number it locks onto to MARK a waypoint.

 

You might be looking at 700' on the Display. MARK a waypoint and it might lock in 640'. What the ...? If you wait long enough, eventually when you see 700' you get darn close to 700'. Of course you could just edit the number if you were sure what it should be.

 

I paid about $100 extra for the Electronic Compass AND Barometric Sensor combo. I think the Compass is easily worth $75, but some days I'm not sure the Barometric Sensor is worth $25.

 

Note for anyone interested. There is another feature I have never used but sounds interesting. You can set the Barometric Sensor to be in "Fixed" or "Variable" mode. If you are on the Water or spending the day at a level surface Base Camp, you can set it to Fixed Mode. Any change in pressure would have to be due to changing weather conditions. If you are going to actually be going up and down in Elevation during the day, set it to Variable.

[+JohnnyVegas]

one option, if you have a TOPO map and know your position on the map you can find your elevation from your map and then enter it into the your altimeter.

In geocaching having your alt. handy may be more of conversation piece if you are only out for a day of caching. But if you are in the back country you can use your barometric preasure as an indicator of a storm front comming in.

[HIPS-meister]

My experience with elevation-figures, with several GPSes, is that they're not particularly useful, nor particularly accurate. In terms of a waypoint, this figure is unimportant.

[+Cardinal Red]

HIPS-meister Posted on Mar 10 2005, 09:55 PM

My experience with elevation-figures, with several GPSes, is that they're not particularly useful, nor particularly accurate. In terms of a waypoint, this figure is unimportant.

 

You just summed up in one line what I took 5 posts to say. I should appoint you to be my editor.