Waypoint Averaging And Placing A Cache

[+obsidianspider]

I'm getting ready to place my first cache and while I've found a great location for it, I want to make sure I get the coordinates right. I've been to some hides where the coords were pretty far off. I was curious for those of you with some hide experience, do you do waypoint averaging when coming up with your coordinates? If so, how many samples do you take before you're confident with the coordinates?

[+wesleykey]

What kind of GPS do you have? THe garmin 60 series will let you average a waypoint, but with other models you may need to mark your spot 3 or 4 times and manually average.

[+obsidianspider]

What kind of GPS do you have? THe garmin 60 series will let you average a waypoint, but with other models you may need to mark your spot 3 or 4 times and manually average.

I have an Oregon 400t with the 2.97 beta software that includes waypoint averaging. I took a sample (required me to wait 60 seconds), but I've heard that 3 or 4 averaged samples is a good amount. Is that overkill?

Edited May 7, 2009 by obsidianspider

[+Tequila]

Here is a very interesting article, by Garmin, on waypoint averaging that will give you some guidance.

 

http://garmin.blogs.com/softwareupdates/trail-tech/

[+Nalarangka]

What kind of GPS do you have? THe garmin 60 series will let you average a waypoint, but with other models you may need to mark your spot 3 or 4 times and manually average.

 

I am one of those who has to manually mark waypoints...I have a etrex H and I usually mark the spot three times...with a little bit of wandering around and coming back to ground zero between marks. I have got around 30+ hides when my team hides are added and I have seldom had any complaints about coords being way off.

[+obsidianspider]

That article was great! Thanks

 

For optimal results, at least 4-8 samples should be collected spaced at least 90 minutes apart (allowing the satellite constellation sufficient time to change).

[knowschad]

Here is a very interesting article, by Garmin, on waypoint averaging that will give you some guidance.

 

http://garmin.blogs.com/softwareupdates/trail-tech/

 

Fascinating article! Good to see an authoritative treatise on the matter instead of the simple forum bantering that sometimes goes on over in the GPS & Tech forum.

 

I like to average around 200 samples, but will often cut that short if I don't see a change in a minute or so. What I'm doing must work, because I often get logs stating that my coordinates were "right-on".

[+Konnarock Kid & Marge]

I'm getting ready to place my first cache and while I've found a great location for it, I want to make sure I get the coordinates right. I've been to some hides where the coords were pretty far off. I was curious for those of you with some hide experience, do you do waypoint averaging when coming up with your coordinates? If so, how many samples do you take before you're confident with the coordinates?

I use a Garmin 60csx, which as stated earlier, does averaging. I usually walk, turn, etc. to get the best accuracy reading then let the GPSr average for 200 or so readings.

[+Konnarock Kid & Marge]

Here is a very interesting article, by Garmin, on waypoint averaging that will give you some guidance.

 

http://garmin.blogs.com/softwareupdates/trail-tech/

 

Thanks for the most interesting article.

The only problem is time. Taking that amount of time to take several samples is sometimes impossible or on really long and difficult hikes to the cache hiding spot, returning is difficult.

Thanks for the reference.

[+Knight2000]

Here is a very interesting article, by Garmin, on waypoint averaging that will give you some guidance.

 

http://garmin.blogs.com/softwareupdates/trail-tech/

Thanks!

 

How do you get that waypoint averaging icon on the Oregon? I don't have it.

[+StarBrand]

A common misconception of many outdoor GPS device users is they need to average every waypoint they mark. However, modern advanced GPS chipsets do significant amounts of calculations and filtering before reporting a position.....

 

Did some of you miss the opening part of that article??

 

I have not averaged most of my waypoints for years - and nobody complains about the coordinates on my caches. The way I look at is this - one of three things is going to happen when I average - and only 1 of the three helps.

1. I have bad sat geometry and weak signals - if I average - I just average bad data.
   
2. I have good sat lock and good geometry, and good conditions - no averaging necesary because of conditions - single read is good.
   
3. I have so-so sat lock and just ok sat geometry - averaging might throw out a piece of or 2 of garbage data and actuallys helps -a bit.
   

I seen several recent thread imply that you "must" average or you will always have poor coordinates - that is just not true.

[Clan Riffster]

One of my units is the 60CSx, with the averaging feature. When I first picked up on this feature, I would set the unit at ground zero and let the averaging software work its magic for several minutes. In checking back on these caches on later dates, I found these had the least accurate coords. My latest method is rather different. I mark ground zero when I place the cache, then I walk off at least 100' toward the cardinal points. I return to ground zero, marking the coords after a few seconds of settling. Then I average these 5 waypoints for the final. Seems to work well.

[+obsidianspider]

It's part of the 2.97 beta software and works very well.

 

I got the link from this post: http://forums.Groundspeak.com/GC/index.php?showtopic=220553

[+Kealia]

FWIW,

 

I have used a Magellan SporTrak Pro since I started. I let it sit at the cache site for 60 seconds to average and then mark the coords. I've never had a complaint about bad coords.

 

Honestly, unless it's a tough location for signal I think way too much is made of this.

Edited May 7, 2009 by Kealia

[+3doxies]

When we used a Maggie MeriGold, we would avg for about 1 min, walk away, come back and avg for 1 min, repeat once again, then take the average of the three...seemed to work well, and we usually got good agreement between each of the 3 readings. With the 60CsX, have usually let it avg for about 200 readings...again, seems to have worked well. In limited experience with the DeLorme PN-40, we've let it average for approx 100 readings...but see very little change in the reading over the last 50 or so of those.

 

EDIT: correct typos

Edited May 7, 2009 by 3doxies

[+mcrow]

People can continue to average their waypoints but I doubt is will improve anything. Maybe I have the wrong idea about how GPSrs and Geocaching works but I thought the idea was to get the cacher into the vacinity of the cache and let them search manually from there.

 

If you mark a waypoint and it will get cachers withint 15-60ft of the cache that seems quite accurate enough.

[+Cache O'Plenty]

15 feet - yes. 60 feet - no. Ever try finding a nano in a rock forest?

 

Seriously, it depends on the type of cache and the locale. If it's a tree hide and there's only one tree for 100 feet, then 30-40 feet is fine. But for bush, ivy, rock, etc. hides where there are a multitude of hidey holes, then accuracy is critical. The 10-15 feet is what I aim for.

 

I've been to hides where they were 60 feet off and that put you on the other side of a river.

 

I realize that the hider's error can be compounded by the finder's error.

Edited May 7, 2009 by Cache O'Plenty

[+Lil Devil]

IMO the built in averaging in all GPSs is a waste of time. I prefer to just mark a waypoint, walk away 100 feet, come back to the cache and mark another waypoint. Walk away 100 feet in another direction, and come back and mark another waypoint. Repeat to get 6 or more waypoints. Average all of them, throwing away any obvious outliers. Been doing this for years and never had a complaint about coords on any of my caches.

[+mcrow]

15 feet - yes. 60 feet - no. Ever try finding a nano in a rock forest?

 

Seriously, it depends on the type of cache and the locale. If it's a tree hide and there's only one tree for 100 feet, then 30-40 feet is fine. But for bush, ivy, rock, etc. hides where there are a multitude of hidey holes, then accuracy is critical. The 10-15 feet is what I aim for.

 

I've been to hides where they were 60 feet off and that put you on the other side of a river.

 

I realize that the hider's error can be compounded by the finder's error.

 

Well, some common sense should be uesed as well. If the owner knows that there is a chance that a lot of people will think the cache is on the other side of the river, maybe they should give a hint. No matter how well averaged your waypoint is the cacher could still be off by 30ft.

[+NYPaddleCacher]

People can continue to average their waypoints but I doubt is will improve anything. Maybe I have the wrong idea about how GPSrs and Geocaching works but I thought the idea was to get the cacher into the vacinity of the cache and let them search manually from there.

 

If you mark a waypoint and it will get cachers withint 15-60ft of the cache that seems quite accurate enough.

 

What is "accurate enough"? IMHO, the idea is *not* to get the cacher in the vicinity and let them search from there. The idea is to get the try and provide accurate coordinates for the geocacher to follow. I've often seen new caches published with concern expressed hoping that the coordinates were good enough. For some hides, getting to the vicinity is good enough if there are relatively few places where the cache might be hidden. For example, I've got a well camo'd container hidden in a tree in the middle of a field. Even if the coordinates were 100' off that tree will draw most gecachers like a magnet. However, if that same cache were hidden in a thick forest, publishing coordinates that were 100' off would make the cache much more diffilcult to find.

 

IMHO, a cache should never be made more difficult to find due laziness in capturing coordinates.

 

The "mark a waypoint", walk away and come back approach has worked well for me. Something else I'll often do is mark a waypoint whenever I have to revisit a cache for maintenance. I can pretty much be assured that the satellite configuration and other environmental factors are going to be different.

[knowschad]

People can continue to average their waypoints but I doubt is will improve anything. Maybe I have the wrong idea about how GPSrs and Geocaching works but I thought the idea was to get the cacher into the vacinity of the cache and let them search manually from there.

 

If you mark a waypoint and it will get cachers withint 15-60ft of the cache that seems quite accurate enough.

 

That explains some of the trouble I had when I was over caching in Hutch!

 

Being off 60 feet will have cacher posting the corrected coordinates in their logs. 60 feet was barely acceptable in the "old days" with old technology. With the chips we have today, I generally try (when hunting a cache ) to get within 10 feet or less of GZ and much more often than not, find the cache very near there.

[+hukilaulau]

A common misconception of many outdoor GPS device users is they need to average every waypoint they mark. However, modern advanced GPS chipsets do significant amounts of calculations and filtering before reporting a position.....

 

Did some of you miss the opening part of that article??

 

I have not averaged most of my waypoints for years - and nobody complains about the coordinates on my caches. The way I look at is this - one of three things is going to happen when I average - and only 1 of the three helps.

1. I have bad sat geometry and weak signals - if I average - I just average bad data.
   
2. I have good sat lock and good geometry, and good conditions - no averaging necesary because of conditions - single read is good.
   
3. I have so-so sat lock and just ok sat geometry - averaging might throw out a piece of or 2 of garbage data and actuallys helps -a bit.
   

I seen several recent thread imply that you "must" average or you will always have poor coordinates - that is just not true.

Me too. I've been using an eXplorist 500 for a few years now and I just set it near the cache (or hold it above the cache if there's tree cover) for maybe two or three minutes and mark it. I haven't heard any comments about coords being off since my third hide.

Edited May 7, 2009 by hukilaulau

[+mcrow]

People can continue to average their waypoints but I doubt is will improve anything. Maybe I have the wrong idea about how GPSrs and Geocaching works but I thought the idea was to get the cacher into the vacinity of the cache and let them search manually from there.

 

If you mark a waypoint and it will get cachers withint 15-60ft of the cache that seems quite accurate enough.

 

That explains some of the trouble I had when I was over caching in Hutch!

 

Being off 60 feet will have cacher posting the corrected coordinates in their logs. 60 feet was barely acceptable in the "old days" with old technology. With the chips we have today, I generally try (when hunting a cache ) to get within 10 feet or less of GZ and much more often than not, find the cache very near there.

 

I only own one cash that I recently placed and has two finds but so far nobody has had trouble with my waypoint and I did a one shot. Also, I think most everyone in the area does the same thing and I've had no trouble finding caches.

[+WHO-DEY]

I did it last night. I like it. I will do again!

[+slukster]

I use both methods when averaging coordinates. I set the GPSr down and use the averaging feature on my Garmin Venture HCX for about 100 readings. I then walk away and come back from a different direction and do it again. I do this at least 4 times so I end up with 4 coordinates to average. Most times the coordinates are differnt by 1 or 2 digits. Other times it is off by more.

 

I know this isn't realistic for most cachers but what I usually do is go out into an area scoping out cache locations without actually placing a container. Sometimes I have cache containers with me to at least see what size will fit where but I don't usually place the containers. I take at least 2 readings using the above method. I then go home and get the cache together and return another day/ time to place the container. At this point I take another 2 or more readings. I then average them from the two different days. I do this because I usually like to place the cache name & number on the cover of the log book and a FTF certificate in the cache and most times the name of the cache is determined after finding the cache location. I often find that the coordinates are off by over 20 ft from one day to another so this gives me a more accurate reading.

[+BCandMsKitty]

I usually take 4 readings, walking away 100 feet or so, between each. I always watch my accuracy readings and usually I am getting 10 feet accuracy or so. If the accuracy is off, I don't take the reading, but hang around until I get good readings. I average the four readings and post the coordinates. Many times I get logs saying the coords are right on, so I think this is all I need to do.

Whenever I go to do maintenance, I do a go-to and check the coords again that way. There's no way I would do 100 readings! IMO, that is extreme overkill!

[+briansnat]

A common misconception of many outdoor GPS device users is they need to average every waypoint they mark. However, modern advanced GPS chipsets do significant amounts of calculations and filtering before reporting a position.....

 

Did some of you miss the opening part of that article??

 

I have not averaged most of my waypoints for years - and nobody complains about the coordinates on my caches. The way I look at is this - one of three things is going to happen when I average - and only 1 of the three helps.

1. I have bad sat geometry and weak signals - if I average - I just average bad data.
   
2. I have good sat lock and good geometry, and good conditions - no averaging necesary because of conditions - single read is good.
   
3. I have so-so sat lock and just ok sat geometry - averaging might throw out a piece of or 2 of garbage data and actuallys helps -a bit.
   

I seen several recent thread imply that you "must" average or you will always have poor coordinates - that is just not true.

 

I agree. If you have a unit that has an averaging feature then it can't hurt to use it, but otherwise its a waste of time. If you have a bad signal or bad sat alignment you are averaging bad data. If you have a good signal and sat alignment you'll get a good read and averaging is pointless.

 

To get a useful average you need to return to the spot over a period of time. All that for an additional 5 or 6 feet of accuracy, which is insignificant in the geocaching world.

 

I have over 270 hides and I rarely average and rarely receive complaints about my coordinates. In fact for the few caches where I have received complaints, most were averaged.

[+Cache O'Plenty]

When I place a cache, I usually just set the unit to averaging and set it down at GZ. Then I finish up the cache, add the title to the log, checking the swag and place the cache, etc. Then I check the GPS. By then, it's averaged at least 50+ times anyway. If the accuracy shows anything below 10.0 feet I feel I'm good to go. I might do it again if I'm not in any rush or the accuracy is >10.0 feet but that usually ends up with, at most, a .001 difference (or 5 feet), not enough difference and I can't average two readings that are only .001 different anyway.

[+Tequila]

Here is a very interesting article, by Garmin, on waypoint averaging that will give you some guidance.

 

http://garmin.blogs.com/softwareupdates/trail-tech/

Thanks!

 

How do you get that waypoint averaging icon on the Oregon? I don't have it.

 

Install the latest firmware. 2.97Beta

 

Setup / Main Menu / Waypoint Averaging

[Skippermark]

If the area is tricky reception-wise, I'll walk 100 feet away and come back from a different direction and mark another waypoint. I'll do that a couple times. If they're all similar, I call it good and move on, tossing out any that are "way out there."

 

Most people say my coords are "spot on."

[+slukster]

There's no way I would do 100 readings! IMO, that is extreme overkill!

 

I think you misunderstood what my 100 readings are. I don't go back and forth 100 times and then average the 100 readings. Using the Averaging feature on my GPSr I let it sit in a spot for around 5 minutes until it takes at least 100 readings (this is done by the GPSr). I then mark it and come back 3 more times from different directions and do the same. Takes no more than 15 - 20 minutes to do.

[+Don_J]

FWIW,

 

I have used a Magellan SporTrak Pro since I started. I let it sit at the cache site for 60 seconds to average and then mark the coords. I've never had a complaint about bad coords.

 

Honestly, unless it's a tough location for signal I think way too much is made of this.

 

Agreed.

I put my 60CS at GZ, hit AVG and walk away for about a minute. I walk away so that I'm not blocking something important with my body, like a satellite. When I'm finished, I walk about a 100' away, set it up to go to my new waypoint and see where it brings me. If it's not to my new cache, I start over. Out of 135 hides, I've only had to go back to one of them because people were having problems.