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Chipper3

What is best practice for Garmin 64st waypoint averaging

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I am interested in using waypoint averaging feature on my Garmin 64st.

 

What is best practice?

 

I incorrectly  thought that I should just stand in one place and activate averaging.  Or should initiate  but stop and then come back at another reading for that same waypoint in the averaging dialog and repeat .  Different days different months, different times, etc.

 

 

Or....?

 

Chipper 3

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14 minutes ago, Chipper3 said:

I am interested in using waypoint averaging feature on my Garmin 64st.

 

What is best practice?

 

I incorrectly  thought that I should just stand in one place and activate averaging.  Or should initiate  but stop and then come back at another reading for that same waypoint in the averaging dialog and repeat .  Different days different months, different times, etc.

 

 

Or....?

 

Chipper 3

 

Here's Garmin's suggestion for a start:  https://www8.garmin.com/manuals/webhelp/gpsmap64/EN-US/GUID-DC65C2FC-0EA3-4182-9B6D-8DB8E4125B56.html

 

It's probably way overkill for placing a cache.  You need a lot of samples at many times to get a suitable "average", and if you don't do all of that, then what's the point?  And then it's only an average of calculations of your own device.

  

For Geocaching purposes, I get pretty decent coordinates by allowing the device to settle down, then taking a bunch of single waypoint snapshots and picking the one I see most often each time I return (while setting up my cache, for example).  I get compliments on the good coordinates, without "averaging".  I ain't got time for that.  :)

 

I have tried various ideas for "averaging" at some tricky caches that nobody ever found, in case it's some special hoodoo that might bring me luck.  So far, no luck.  :cute:

 

 

Edited by kunarion

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Thank you, kunarion...

 

Gotcha'

 

So, what is your favorite method for deciding that device has "settled down?"

 

 

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20 minutes ago, Chipper3 said:

Thank you, kunarion...

 

Gotcha'

 

So, what is your favorite method for deciding that device has "settled down?"

 

 

 

Place it on a stump or in the ground or hang it on an object, see if it's finished jumping all over the place.  If it's directly on the cache spot at that moment, you might be golden.  I challenge myself to get it down to the last couple of feet, but you don't have to be all that accurate.  Once people are within 30 feet of the cache, they're looking less at the GPS and more for likely hiding spots.  This isn't rocket surgery.  :cute:

 

You can do every earthly calculation possible, and yet have something a little off once it's published.  Finders will log that it's a little off, sometimes in which direction, and they might post some coordinates.  Sometimes it's due to a typo when building the cache, sometimes it's just that people are getting better readings when they try it.

 

The main thing is to go find a bunch of caches, and get a feel for what your GPS tells you, compared to where you actually find the cache.  Return to a visited place, and even then you see different readings at times.  You begin to know when the GPS is struggling and when it's cool.  I think it's easier with practice. :)

 

Edited by kunarion

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1 minute ago, Chipper3 said:

I like your bare-bones techniques and easy to understand directions.

 

If you get caught up in "averaging", you'll spend a lot of time at your cache spots, with no particular improvement for Finders.  Maybe if it's a place that's walled-in and readings are all over the place (a forest valley or whatever), it then might be worth trying "averaging" to see how it goes.  But not all the time.

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20 minutes ago, Chipper3 said:

So, what is your favorite method for deciding that device has "settled down?"

 

I put the GPSr on something flat within an arm's length, and have a smoke.  :)    The other 2/3rds would have a snack (uncrustables are awesome). 

Still flicks back n forth a foot or two...

We've tried averaging, but for us it was best to simply walk away and come back.  I like to walk anyway.  ;)

Sometimes we'd come back another day (if raining or overcast our first time out) , before we'd finally place the cache.

Doesn't matter, you know some guy will log that his new whizz-bang super gizmo is so accurate you're twenty feet off.     :D

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Just now, cerberus1 said:

some guy will log that his new whizz-bang super gizmo is so accurate you're twenty feet off.     :D

 

That's what irks me most about setting coordinates.  Funny, everybody else except that guy found it just fine using the posted coords.  :P

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While we are talking about accurate coords -  What are your thoughts on just going to google maps or google earth and drilling down to a recognizable spot (satellite image) and grabbing a coord off of the map?

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56 minutes ago, Chipper3 said:

While we are talking about accurate coords -  What are your thoughts on just going to google maps or google earth and drilling down to a recognizable spot (satellite image) and grabbing a coord off of the map?

 

I look at the map to see where my waypoint shows up, to help me confirm I've got it.  But maps are made of drawings or photos stitched together.  They line up better in some places than others.  Get good at taking GPS waypoint snapshots while standing at the cache site.  Many great cache spots are not at a point you can see on a map.

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One round of averaging ought to do it. It takes anywhere from 2 to 5 minutes, depending on your location and timing, to get a full reading. Yes, Garmin recommends coming back to the location and doing more averaging, but for geocaching, it's not that imperative. For most uses, it's not that important.

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The placement guidelines say you have to go to the place and measure coordinates of a cache when submitting it. Using Earth or similar technologies for double checking ("it's by the third tree...") a submission, but it's not enough on its own.

The photo stitching thing is somewhat true. Fifteen years ago, when imagery was mostly satellite and before Landsat 7, there were visible issues in image registration and orthorectification. Google has gotten much better at this over the years and it's pretty rare to see meaningful alignment issues these days. They've even gone back in many cases and tried to snap some of the more footloose images in the historical imagery databases, but if you animate a time series, you can still see some jitter.

If you're interested in an accessible look at how those maps are made, there was a really good video explaining the process at https://www.youtube.com/watch?v=suo_aUTUpps It's a little fluffy at the beginning, but Gopal and the rest of the crew explain it quite well.

Source: former engineer at Google that worked on Earth for 13 years.

 

 

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10 hours ago, kunarion said:

For Geocaching purposes, I get pretty decent coordinates by allowing the device to settle down, then taking a bunch of single waypoint snapshots and picking the one I see most often each time I return (while setting up my cache, for example).  I get compliments on the good coordinates, without "averaging".  I ain't got time for that.  :)

 

 

We have good luck with our coordinates too. We walk up from a distance to the cache and then wait a minute for the coords to adjust, take a photo, and then repeat two more times. I then get on the computer at home and google each coordinate...their satellite map shows which coordinate brings you to the exact location of the cache we hid. 

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As RobertLipe states, even Google Maps imagery is not always perfect. I frequently check the same data against google maps for location verification and find that their aerial imagery 'moves around' frequently. Same coordinates today will very likely show in a slightly different location in the next release of their data. I am not sure if this 'random offset' is intentional or accidental, but it is real.

 

Also stated, it is a requirement of publishing a geocache that the coordinates for the location be taken at the location live with a GPSr device.

 

Some information on Waypoint Averaging is available at GPSrChive > How To... > Waypoints

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Like RobertLipe said though, google has gotten much better at this over the years and it's pretty rare to see meaningful alignment issues these days.

I haven't had a problem yet with google maps, thankfully. And I always do the coordinates at the location first before checking google maps. Actually, I walk up to the cache three different times and always get three different coordinates on my GPS. Funny how that happens. Comparing them to google maps helps me decide which coord is the most accurate. It's what works for me. 

 

 

Edited by HunterandSamuel

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And back on topic:
The amount of averaging you need to do to be confident of at least decent co-ords depends heavily on the location :If the satellite constellation is favourable and the area is nice and open, you will probably get a reasonably accurate waypoint very easily and quickly. However, in a dip or valley, next to a cliff or rock face (or the man made equivalent) or under a heavy tree canopy a bit more effort is needed.

In good signal spots I'll generally just do as cerberus describes (but in my case , the wait will feature chocolate ), if the location seems a bit difficult for a good signal (especially if the GPS accuracy field falls below 3m)  I'll use the waypoint averaging facility too, and whatever my assessment of the area, I always walk away at least 20m and then head back to the location from a different direction to the first approach, using the waypoint I made to check it.

 

I always return to GZ at a later date, either to actually place the container or to check it before pressing the publish button, so routinely check the co-ords on another day as well. I like it when finders say my co-ords were spot on :)

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And you can always use a tool like this to determine the best day and time for constellation visibility.

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Remember that you can also provide a text description of where it is hidden, either in the description itself or in a hint. This way once a seeker gets to your coordinates, they can just put down the GPS and search locations that match your description.

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13 hours ago, Chipper3 said:

I incorrectly  thought that I should just stand in one place and activate averaging.

This is correct, by the way. Once averaging starts, you don't want the GPS to be moving until you stop it and save the waypoint. Averaging can be done multiple times and Garmin recommends that you wait at least 90 minutes between averaging sessions because if any errors are due to bias in the satellites, you want to give the bias a chance to shift letting the averaging average out the biased noise. Otherwise, you're recording the same bias and your average won't move much. 

But generally speaking, if I do the averaging, and then my GPS says I'm more than 10 feet away from the point I just marked, it's usually because I was hasty and didn't let the position settle before starting the averaging. In which case I'll usually do a second, independent averaging and get a more stable estimate.

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5 hours ago, hal-an-tow said:

In good signal spots I'll generally just do as cerberus describes (but in my case , the wait will feature chocolate )

 

+1
 

Some COs toss the pill bottle into a bush, turn on "GPS", hop back in the car and leave.  The device shows most anything at first, usually that's the spot where it was last used.

 

One of the best ways to get Geocaching coordinates is to stop at a spot and wait.  If "averaging" causes people to stop and wait, cool.  I may routinely suggest 'stop at your cache spot and ... ahem... "averaging" for a while'. B)

 

 

Edited by kunarion
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Thank you, Thank You to all the responders for their excellent and experienced comments.

I conclude that:

1.  I will walk to a spot

2. Let my GPSr "settle down."  aka wait a few minutes.

3.  I am going to take a quick MARK reading just to have some extra data.

4. I am going to set down the GPSr  and use the waypoint averaging feature  to create an averaged waypoint but not revisit that same waypoint later to add more data in the averaging dialog.

5.  I am going to walk away  150 feet and then return to spot.

6. I am going to repeat the  waypoint averaging but create a brand new 2nd averaged waypoint.  And average those two values.

7.  I'll check on google earth as a sanity check but rely on the GPSr generated coords.

 

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20 minutes ago, Chipper3 said:

Thank you, Thank You to all the responders for their excellent and experienced comments.

I conclude that:

1.  I will walk to a spot

2. Let my GPSr "settle down."  aka wait a few minutes.

3.  I am going to take a quick MARK reading just to have some extra data.

4. I am going to set down the GPSr  and use the waypoint averaging feature  to create an averaged waypoint but not revisit that same waypoint later to add more data in the averaging dialog.

5.  I am going to walk away  150 feet and then return to spot.

6. I am going to repeat the  waypoint averaging but create a brand new 2nd averaged waypoint.  And average those two values.

7.  I'll check on google earth as a sanity check but rely on the GPSr generated coords.

 

 

Typically an Averaging app will allow you to continue gathering more data whenever you return, and in theory that makes the computed point even better.

 

Most Geocachers have reasonable consumer GPS readings and are accustomed to coordinates that aren't particularly, you know, "average" :huh:.  So as Mineral2 said, post a great hint so that people have an idea of where to look upon arrival.

 

Edited by kunarion
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47 minutes ago, kunarion said:

Typically an Averaging app will allow you to continue gathering more data whenever you return, and in theory that makes the computed point even better.

 

Yes, My Garmin 64ST  does that.  I guess one can only do so much to try and be accurate.  

I have adopted the technique you suggest and include a veiled clue as part of the description usually in the context of the story.

For example, the coords take a seeker  to a spot and I include tha you should enter 7th Heaven and use the following projection.  7th Heaven is a the 7th basket on a frisbee golf course.

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One of my caches was placed in an area in which I just could not get a stable reading. The averaging took almost 10 minutes and even then, my location kept bouncing around over 50 feet in any direction from where I was. I ended up coming back a second day and still couldn't get a great reading, which meant that any finder coming along is also going to have a problem. I ended up giving specific directions as to which stump it was hidden in (there are many), and it has helped. That was by far the worst I've had trying to place a hide.

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3 hours ago, Mineral2 said:

One of my caches was placed in an area in which I just could not get a stable reading. The averaging took almost 10 minutes and even then, my location kept bouncing around over 50 feet in any direction from where I was. I ended up coming back a second day and still couldn't get a great reading, which meant that any finder coming along is also going to have a problem. I ended up giving specific directions as to which stump it was hidden in (there are many), and it has helped. That was by far the worst I've had trying to place a hide.

I hear you!  I want to believe that the GPS system yield super accurate results but it's not the case IMHO.  Too may variables and then there is the problem of the seeker's iphone being inaccurate and the satellites are in a different position 6 months later, etc. All we can do is try our best to use accurate coords and offer some clues to help zero in on the actual location.    For example today, I use my Garmin 64ST to collect  a trillion readings to average a spot at 100% and then revisited that spot 2 more times to add to the "accuracy."   The I used my device to find my way to the recorded spot and I was 25 feet off.  I used my iPhone Geocache app and was 35 feet off in a different direction.  Then I used another device used for hiking and was also off.    I think I need to abandon the thought that I am dealing with pin-point accuracy. =)    I will always give the cache hunter a clue along with the coords.

 

This inaccuracy is why the military (even with non wobbling gps signals) uses lasers to guide bombs to the targets.  =)

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Hi... Can the GPSMAP 64st be user selected to calculate elevations by GPS data only? That is, in addition to the two methods of using barometric data only, or barometric reading modified by auto calibration with GPS readings, can it use only GPS data exclusively by user options?

 

order pcb

Edited by LariPilot

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On 1/26/2020 at 9:25 PM, cerberus1 said:

I put the GPSr on something flat within an arm's length, and have a smoke.  :)

We've tried averaging, but for us it was best to simply walk away and come back.

I have found the "walk away" option to be the most valuable for me. I start with averaged coordinates as above, then walk away and navigate back. Make a mental note of how far away it thinks I am. Walk away in the opposite direction and navigate back. Again note the reported distance. Then edit the saved coordinates to reflect that. So for example if a couple walkaway/walkbacks say the cache is still 15 ft north of reality, I'll subtract .002 from the N saved coords. Repeat with E/W. 

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