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As COs let's make sure to verify cache coords with imagery


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This is just a friendly reminder for COs to verify the exact coordinates of their caches using Google maps imagery when possible.

Let's face it - using smartphones is often the way caching is done these days, so COs (including myself) get coordinates with their caching app's compass. While there's no issue with this method of getting coordinates, it may be less accurate than using a conventional GPSr. So it becomes even more important to verify the location of the coordinates on Google maps or similar imagery in order to ensure accuracy. I only have four hides but I've had to make adjustments based on seeing the coordinates from my app didn't line up on the map with where I knew the cache was.

What made me think of this issue was trying to find a cache a few days ago and logging a DNF bc I came up empty.

Today I came back and used my geosenses and expanded my search area. I know, I know, I should have done this in the first place. BUT the imagery on the app clearly showed the cache location on one side of a gravel road when the true location ended up being on the opposite side of the road. That's my beef - especially with urban caching (but of course not limited to urban caching) we as COs need to make sure our cache coords are accurate to the digital map.

To me, achieving coordinate accuracy gets to the essence of geocaching - finding a container based on GPS location.

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This is just a friendly reminder for COs to verify the exact coordinates of their caches using Google maps imagery when possible.

Allow me to be the first (but probably not the last) to point out that, depending on the location, Google Maps can be up to hundreds of feet off. They've improved over the years, but I would never depend on Google Maps to be the final arbiter of whether GPS coordinates are accurate.

 

--Larry

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This is just a friendly reminder for COs to verify the exact coordinates of their caches using Google maps imagery when possible.

Allow me to be the first (but probably not the last) to point out that, depending on the location, Google Maps can be up to hundreds of feet off. They've improved over the years, but I would never depend on Google Maps to be the final arbiter of whether GPS coordinates are accurate.

 

--Larry

Yeah a big +1 on this. The last thing I would use is Google maps. Coordinates being off by 25 feet or so just doesn't bother me, its normal error. More than 50 feet? Well I just might post alternate coordinates in my log. I would never use Google maps to check the coordinates.

 

Edit: Also in forested area Google maps are all but worthless to establish the coordinates. Which tree is that cache hidden by now?

Edited by jholly
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This is just a friendly reminder for COs to NOT verify the exact coordinates of their caches using Google maps imagery.

 

Trust your device, not the maps.

 

Online maps, be it Google or some other are tile OVERLAYS placed upon a coordinate grid. You cannot map an orb (the earth) and transfer it to a flat map without distortion, severe in its entirety, less severe but more widespread using tiles.

 

Actually, the same applies to flat paper maps, also.

Edited by Gitchee-Gummee
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I'd like to echo the two above me and say that your gps may have been out on the day and google maps is often out for the sort of accuracy we need.

 

I find when I'm trying to work out where i am for cache placement purposes is best to ignore the finding apps altogether and use an averaging app. It takes readings over a ten or twenty minute time span then takes the average of those readings, this assists to remove much of the error.

 

THEN have a look at it with Google maps (to ensure you are in the right general area) THEN find your GZ again using your coordinates you have gathered.

Edited by Tassie_Boy
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This is just a friendly reminder for COs to NOT verify the exact coordinates of their caches using Google maps imagery.

 

Trust your device, not the maps.

 

Online maps, be it Google or some other are tile OVERLAYS placed upon a coordinate grid. You cannot map an orb (the earth) and transfer it to a flat map without distortion, severe in its entirety, less severe but more widespread using tiles.

 

Actually, the same applies to flat paper maps, also.

 

I'm with those who don't think using on-line sat images after placement is a good idea. Use it for scouting out what may be a good location, but use a GPS device (and take at least 5 readings) to determine cache placement.

 

BTW, there's a current thread that mentions people moving caches. Ever consider the possibility that the cache was in the correct place for the coordinates, but someone moved it to what they thought was a "better" place?

 

Austin

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Before this gets out of hand, let me clarify.

When I said Google maps I meant it as an example of digital imagery.

The fact is most cachers now use an app, so maybe it's just me being preferential to app use but the coords should match what's on the ground.

I know I'm about to hear mapmaking and earth visualization lessons ad nauseum. Go!

(I just like poking bears)

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Before this gets out of hand, let me clarify.

When I said Google maps I meant it as an example of digital imagery.

The fact is most cachers now use an app, so maybe it's just me being preferential to app use but the coords should match what's on the ground.

I know I'm about to hear mapmaking and earth visualization lessons ad nauseum. Go!

(I just like poking bears)

Your statement about most cachers now using an app is not a fact!

It my be in your experience, but In my circles, I don't know anyone that caches exclusively with an app. In my experience, most cachers use a hand held, dedicated GPSr.

Be that as it may, if proper multiple coordinates are taken when the cache is hidden, and verified by walking away and returning to the cache following those coordinates, then the coords will match what's on the ground!

If a cache hider isn't going to take the time to verify their hide, while hiding, there's no way they'll bother with verifying with anything else, and if they're taking coords with an app, and those coords are off, and then using the same phone to verify with a map app, chances are the verification will will simply verify the same wrong coords!

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According to the guidelines, "You must visit the cache location and obtain the coordinates with a GPS device."

 

Verifying the exact coordinates is good. Enter your coordinates into your device and use it to navigate to the cache location several times, approaching from different directions each time, approaching from at least 100ft away each time. No matter which way you approach, the arrow should point at the cache location.

 

Verifying the general location with digital imagery/maps is good. But as others have pointed out, digital imagery can be hundreds of feet out of calibration. It is not good to rely on them to verify your exact coordinates.

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...but the coords should match what's on the ground.

Correct, however that doesn't involve a map or imagery at all. It involves going to the spot in person - on the ground - and using a device to tell you what the coordinates are.

 

The extent of map- or imagery-use to confirm the accuracy of coordinates should be to confirm that you're in the ballpark. That's all. For example, if the imagery shows your coordinates way out in the middle of the ocean or some other far away place, then you know there's something wrong and need to either check for typographical errors or revisit the site to take new coordinates. If the imagery shows your coordinates anywhere within a few hundred metres, then you're now done with using the imagery. Never, never, never, never* adjust your coordinates based solely on satellite imagery. The imagery's alignment on the geographical grid will never be accurate. It may be "close enough" in some areas, but it isn't consistent and shouldn't be relied upon.

 

As for your DNF and the cache being on the other side of the gravel road, that may be a great example of how the imagery can be inaccurate (assuming the CO's coordinates are fairly accurate). If you had followed your device to the coordinates, rather than referencing its position to landmarks on the satellite imagery, I bet you'd have had better luck. This game is about navigating to a set of coordinates, not a visual spot on an image.

 

*...never, never, never, never, never, never, never, never...

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Before this gets out of hand, let me clarify.

When I said Google maps I meant it as an example of digital imagery.

The fact is most cachers now use an app, so maybe it's just me being preferential to app use but the coords should match what's on the ground.

I know I'm about to hear mapmaking and earth visualization lessons ad nauseum. Go!

(I just like poking bears)

Your statement about most cachers now using an app is not a fact!

It my be in your experience, but In my circles, I don't know anyone that caches exclusively with an app. In my experience, most cachers use a hand held, dedicated GPSr.

Be that as it may, if proper multiple coordinates are taken when the cache is hidden, and verified by walking away and returning to the cache following those coordinates, then the coords will match what's on the ground!

If a cache hider isn't going to take the time to verify their hide, while hiding, there's no way they'll bother with verifying with anything else, and if they're taking coords with an app, and those coords are off, and then using the same phone to verify with a map app, chances are the verification will will simply verify the same wrong coords!

 

Guess our mileage will vary. :) In our area, every new cache, placed by a newer cacher, is placed using a phone. I've met several of these owners and for the most part, they've done pretty good with their coordinate taking. However, there have been quite a few newer caches, placed by newer people, that were a bit off from the listed coordinates. Matter of fact, i just found one the other day that was 4 miles off. Luckily there was enough information in the cache description for us to make the find. The thing is, if that owner would have just looked on their cache page (the map itself), they would have instantly noticed that their coordinates were off.

 

As far as google maps go, the coordinates are right on the money every time i use it. This is with the mouse pointer on a computer. On the otherhand, the caches will likely not be in the right spot on google earth when using the geocaching google earth viewer. Matter of fact, the caches themselves will jump around when you look at it. I'm not sure why this is but it's done it from day one. :blink:

 

Imo, the OP has an idea that could be of benefit to many cachers. It doesn't necessarily have to be spot on but it sure wouldn't hurt for some of us to do a quick glance at a map to make sure we are at least in the ballpark!

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To me, achieving coordinate accuracy gets to the essence of geocaching - finding a container based on GPS location.

 

Then why on earth would you suggest that people defer to flat aerial images on a computer screen that can be hundreds of feet off from actual coordinates?

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To me, achieving coordinate accuracy gets to the essence of geocaching - finding a container based on GPS location.

 

Then why on earth would you suggest that people defer to flat aerial images on a computer screen that can be hundreds of feet off from actual coordinates?

 

Narcissa, do you have any information to add to this topic?

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In my home area and in my reviewer territory, Google aerial imagery is reasonably accurate. So, each time I review a cache, I look at the aerial image to make sure it matches the information provided on the cache description and in the CO's private reviewer note. If the hint is "guardrail" and the aerial photo shows a grassy field, I ask the CO to double-check their coordinates -- not that they're "wrong," but I point out what I saw and ask them to make any necessary adjustments. I have that dialogue several times each week during the busy hiding season.

 

Once each month or so, a CO insists their coordinates are accurate and that "you are wrong," or "the maps are wrong." They say enough to convince me to publish the cache. A day or so later, I'll receive an email: "Please help fix the coordinates on my cache. I tried to update them but the website won't let me because it's too far away. The error message told me to write to you."

 

Aerial imagery is a useful, although not definitive, tool for coordinate validation in areas where the imagery is reasonably well-aligned. It is true that this is not the case everywhere. In my experience, the more urban the area, the more accurate the imagery.

Edited by Keystone
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To me, achieving coordinate accuracy gets to the essence of geocaching - finding a container based on GPS location.

 

Then why on earth would you suggest that people defer to flat aerial images on a computer screen that can be hundreds of feet off from actual coordinates?

 

Ummm... maybe because, right or wrong, the OP believed that it was a better method. How about instead, you explain in friendly terms why that is not so, rather than attacking the OP and essentially calling them stupid?

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In my home area and in my reviewer territory, Google aerial imagery is reasonably accurate. So, each time I review a cache, I look at the aerial image to make sure it matches the information provided on the cache description and in the CO's private reviewer note. If the hint is "guardrail" and the aerial photo shows a grassy field, I ask the CO to double-check their coordinates -- not that they're "wrong," but I point out what I saw and ask them to make any necessary adjustments. I have that dialogue several times each week during the busy hiding season.

 

Once each month or so, a CO insists their coordinates are accurate and that "you are wrong," or "the maps are wrong." They say enough to convince me to publish the cache. A day or so later, I'll receive an email: "Please help fix the coordinates on my cache. I tried to update them but the website won't let me because it's too far away. The error message told me to write to you."

 

Aerial imagery is a useful, although not definitive, tool for coordinate validation in areas where the imagery is reasonably well-aligned. It is true that this is not the case everywhere. In my experience, the more urban the area, the more accurate the imagery.

Good advice, and something that I practice as well when hiding. I know what the area *should* look like when I hide a cache, and if the aerial imagery doesn't match what I entered, I can be pretty much assured that I fat-fingered the coords or made some other area. However, simply because the aerial imagery doesn't show the marker to be right exactly on the tree that I hid the cache in, I am not going to tweak my coordinates so that it does.

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Google maps can be a good way of double-checking to make sure you didn't make a huge error in entering the numbers.

 

However, like others have said, they are not always accurate. In some areas, they are really accurate, some not so much.

 

Best to use your device to get the coordinates, to take a few and average them. If you're having trouble getting accurate coordinates, maybe there's someone local who can help you get the most out of your smartphone.

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Before this gets out of hand, let me clarify.

When I said Google maps I meant it as an example of digital imagery.

The fact is most cachers now use an app, so maybe it's just me being preferential to app use but the coords should match what's on the ground.

I know I'm about to hear mapmaking and earth visualization lessons ad nauseum. Go!

(I just like poking bears)

Your statement about most cachers now using an app is not a fact!

It my be in your experience, but In my circles, I don't know anyone that caches exclusively with an app. In my experience, most cachers use a hand held, dedicated GPSr.

Be that as it may, if proper multiple coordinates are taken when the cache is hidden, and verified by walking away and returning to the cache following those coordinates, then the coords will match what's on the ground!

If a cache hider isn't going to take the time to verify their hide, while hiding, there's no way they'll bother with verifying with anything else, and if they're taking coords with an app, and those coords are off, and then using the same phone to verify with a map app, chances are the verification will will simply verify the same wrong coords!

 

Guess our mileage will vary. :) In our area, every new cache, placed by a newer cacher, is placed using a phone. I've met several of these owners and for the most part, they've done pretty good with their coordinate taking. However, there have been quite a few newer caches, placed by newer people, that were a bit off from the listed coordinates. Matter of fact, i just found one the other day that was 4 miles off. Luckily there was enough information in the cache description for us to make the find. The thing is, if that owner would have just looked on their cache page (the map itself), they would have instantly noticed that their coordinates were off.

 

As far as google maps go, the coordinates are right on the money every time i use it. This is with the mouse pointer on a computer. On the otherhand, the caches will likely not be in the right spot on google earth when using the geocaching google earth viewer. Matter of fact, the caches themselves will jump around when you look at it. I'm not sure why this is but it's done it from day one. :blink:

 

Imo, the OP has an idea that could be of benefit to many cachers. It doesn't necessarily have to be spot on but it sure wouldn't hurt for some of us to do a quick glance at a map to make sure we are at least in the ballpark!

 

I agree with you about the cache page map, and I always use that to verify my cache placement. Maybe I misunderstood the OP. I got the impression that the suggestion was to use a map appp on the phone to verify ... not the one on the cache page as you said, with a mouse pointer on a computer.

If the OP is talking about verifying in that way, then I agree.

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On a related note, since the best way to capture accurate coordinates is with your GPS device, not aerial imagery, check out this brand-new Help Center article on taking coordinates with a handheld GPS or smartphone. It's written by our favorite helpful UK geocachers, The Blorenges, who also maintain the "Follow the Arrow" site with many other practical geocaching tips. That site is linked from the Help Center article.

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On a related note, since the best way to capture accurate coordinates is with your GPS device, not aerial imagery, check out this brand-new Help Center article on taking coordinates with a handheld GPS or smartphone. It's written by our favorite helpful UK geocachers, The Blorenges, who also maintain the "Follow the Arrow" site with many other practical geocaching tips. That site is linked from the Help Center article.

 

Thanks for the link. That's a really good article. It even tells you how to manually average coordinates.

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I'm going to go against the grain and say, yeah, it's a good idea to check your coordinates against the space view. If they disagree, you have a problem, but, as others have pointed out, the solution isn't to take the coordinates from the space view. The solution is to go back to GZ and make absolutely sure you have the right coordinates. I normally take the numbers I get from space and use them to try to find the cache. In my area, most times they turn out to be the better numbers, but I don't take them on faith. After you do this a few times, you'll get a feel for whether the space view is accurate -- as it is in my area -- or way off, as it is elsewhere.

 

One thing to watch out for, though: where it's available, Google switches to a 45° view as you zoom in. In my experience, the 45° view is always way off, so make sure to force it back to the straight down view before you do anything.

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I'm going to go against the grain and say, yeah, it's a good idea to check your coordinates against the space view. If they disagree, you have a problem, but, as others have pointed out, the solution isn't to take the coordinates from the space view. The solution is to go back to GZ and make absolutely sure you have the right coordinates.

 

I agree.

 

I routinely look at the the google imagery maps - both as a sanity check of my hide, and also in preparation of finding. Of course if the cache is in the middle of the woods they don't help that much (other than verifying it is pointing to the woods), but if there are landmarks around they are useful. I use them to decide where to park etc.

 

I'm sure it must happen as every time this topic comes up there are loads of posts saying it does, but I've NEVER seen google maps being hundreds of feet off. And that is in 25 countries spread across the globe.

 

I would not alter the coordinates of a hide based on what google maps says. But if google maps is disagreeing with my GPS by hundreds of feet, I would investigate.

 

I have encountered caches where the coordinates in the field were off by 100 feet or more (according to my GPS). In these cases, the google maps agreed with my GPS.

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One thing to watch out for, though: where it's available, Google switches to a 45° view as you zoom in. In my experience, the 45° view is always way off, so make sure to force it back to the straight down view before you do anything.

 

If we're talking about Google Earth here you can actually switch off the automatic 45° tilt on zoom if you want to as it's an option :)

 

1. Click Tools then Options

2. Click the Navigation tab

3. Select the Do not automatically tilt while zooming radio button under Navigation

 

Incidentally, if you've not already done so, if you click on the 3D View tab you can also set the Show Lat/Long setting to Degrees, Decimal Minutes so that it matches the default coordinate format used on geocaching.com :)

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In theory even its not a great idea. The online coordinates show you were it should be. Mathematically. The GPS unit however will behave totally differently onsite. It will behave differently depending on time of day, battery power, environmental issues such as granite, your best bet it as good as possible coordinates via waypoint averaging and tweeking those if possible.

 

Then along comes someone with the same GPS/different GPS/smartphone and says they are way off. So best possible accuracy is all you can hope for. This is unlikely to be the online coordinates.

 

What I would say is that we have found a few caches by looking at the cache placement on zoom and the map and ignored the advice of the arrow on the GPS.

 

Most of us have had the case where we stop to take stock and the cache is supposed to be 80 feet away and suddenly it appears to bring itself to you lol. Or it points at a sheep and starts to move off. One hell of a container that.

 

Your last idea was a good one I thought. This one ... not so much lol.

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There's a big difference between doing a sanity check by glancing at the map in case you've transposed numbers, and assuming that the map is more correct than a GPS reading taken on site.

 

It's no secret that I think very little of smartphone GPS, but I would trust a smartphone's coordinates over a Google map where I can literally see seams between images that don't match up.

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Things to know:

* How accurate is the imagery in your area? (try scrolling around and look for seams)

* Often the road view will be more accurate than the satellite imagery - if you can view hybrid, see how aligned the roads are the imagery (trust the roads more than the satellite; even though the roads can also be wrong; more often, they are more accurate)

* Imagery may be out of date. A waypoint in a field noted as a guardrail may still be correct, but it's a recently developed area. No on would know except the person who's been there.

 

That said, it's never good to begin placement by using satellite imagery. I like that, 'sanity check' - if used, it should only be used as a verification (once all the above shows that the imagery is accurate).

 

And this coming from a phone-exclusive cacher who uses satellite quite often.

Aerials are more useful in the city, and less useful in the rural or in areas with very little visual landmarks and more likelihood of being slightly misaligned.

 

I strongly recommend that when searching for caches you have access to satellite imagery. For one, you don't know how accurate the CO's coordinates are themselves, and you don't know what method or tool they used to place the cache. You could have the most accurate GPS in the world, but if they used (misaligned) aerial, you could still be way off. So, have it handy, so in case you have any problems you can check it. I've often found, especially in high urban areas with tall buildings, COs tend to rely on satellite imagery more than GPS, because regardless of device there will be bounce. Checking the map in those places has in my experience shown the marker spot on the correct location more than otherwise; impossible (or at least ridiculously difficult) by GPS alone. Even if the imagery isn't properly aligned (though much less likely in urban areas), it may be your best bet when searching (dare I say even when hiding).

 

In short, there are times when satellite imagery has its place. But it should never be the first tool for getting a location. At best, once you've determined that GPS reception is next to impossible, then resort to it. And disclaim on the cache page that gps reception at gz is spotty at best. :P (for whatever reason)

 

tl;dr:

- When hiding, always start with reading coordinates first (with proper due process for accuracy). Use maps as a backup. And be sure you are aware of whether the aerial tiles are properly aligned! (and to be kind, disclaim any potential issues on the listing!)

- When finding, use whatever method or tool you're comfortable with, but it's prudent to have access to aerial imagery, regardless of how accurate your device or the imagery is, in the case that the CO used it to place the cache.

Edited by thebruce0
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I've often found, especially in high urban areas with tall buildings, COs tend to rely on satellite imagery more than GPS, because regardless of device there will be bounce. So checking the map typically shows the marker spot on the correct location. Impossible by GPS alone. Even if the imagery isn't properly aligned (though much less likely in urban areas), it may be your best bet when searching (dare I say even when hiding).

 

I've not done much city caching but when I cached in the centre of Manchester (England) I found that my smartphone was WAY more accurate than my trusted handheld GPS unit.

 

I put this down to two things:

 

1. There was a lot of GPS signal bounce / multi-homing caused by the closely clustered tall buildings

2. The cellphone was able to utilise cell triangulation very effectively because of the presence of many more mobile phone masts in the city than one would find in a rural setting.

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Sanity check, yes. It will easily show you if you are in the right park. Exact location, not so much -- it may or may not show which side of the road or path you are supposed to be on. It is a good idea to glance at the location on the map and see that it is generally correct, but not to adjust your coordinates by them.

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fuzzie, that's way oversimplified and highly exaggerated. There are many factors involved in how accurate aerial imagery may be, just as there are many factors involved in how accurate GPS readings may be. Aerial imagery can, indeed, be completely accurate to GPS location. It can also be ridiculous misaligned. You just need to know which it is, where between those two extremes, at whatever location you are.

Edited by thebruce0
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If we're talking about Google Earth here you can actually switch off the automatic 45° tilt on zoom if you want to as it's an option :)

No, I was talking about viewing the space image in google maps. If there's a way to turn off the 45° there, I haven't found it. I only use google earth when I want to look at older imagery.

 

Edited to add: I just noticed that they appear to have gotten rid of the 45° entirely in the new google maps, so it shouldn't be a problem for people using that.

 

That said, it's never good to begin placement by using satellite imagery.

Actually, if I know where I'm going to place the cache in advance, I always start with a location taken from the space view, then see if those numbers lead me to where I'm planning to hide the cache. If they don't, then obviously I've got more work to do. But if they do, I want to give preference to those numbers over any similarly accurate but slightly different numbers I might collect with my GPSr.

Edited by dprovan
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I'm sure it must happen as every time this topic comes up there are loads of posts saying it does, but I've NEVER seen google maps being hundreds of feet off. And that is in 25 countries spread across the globe.

Check out this area. I just did a quick measurement in Google Earth, and the difference between the imagery and the Google road data is approximately 240 feet. Interestingly in this case, however, the imagery is actually aligned almost perfectly (confirmed by my GPS track logs); it's the road data that's misaligned. If you look just to the west and east, the alignment is much better. This just goes to show that you can't rely on the road overlays to be accurate, either. Even if it's accurate in one spot, it can be way off right next door, and there are no seams in the data to indicate where you should look for changes in accuracy.

 

This game is and has always been all about GPS use. Just use your GPS.

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So where is this one? (in Chrome) Link

 

Note: if you use IE the imagery will be different and you won't see the issue.

Probably somewhere out on that pipeline, likely without permission. :laughing:

 

BTW, I looked at it in IE and see the break in the imagery alignment just fine. The difference won't appear or disappear depending on the browser, it will be whether you're using the new or classic Google Maps. In this case, the problem is only present in the new Google Maps.

 

Edit: That does raise another point. Just because the alignment may appear accurate when looking at a spot on the map at home, it isn't guaranteed that your app will be using the same imagery and may not be as accurate.

Edited by The A-Team
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That said, it's never good to begin placement by using satellite imagery.

Actually, if I know where I'm going to place the cache in advance, I always start with a location taken from the space view, then see if those numbers lead me to where I'm planning to hide the cache. If they don't, then obviously I've got more work to do. But if they do, I want to give preference to those numbers over any similarly accurate but slightly different numbers I might collect with my GPSr.

dry.gif ok, well I'm assuming you understand what my meaning was per the rest of my comment.

So strictly speaking, "begin placement by using satellite imagery" is bad wording on my part. The intent was to say that satellite imagery should not take precendent over GPS readings, except in cases where GPS reception is known to be insufficiently accurate compared to aerial alignment (as decribed in the rest of my comment).

If you start a new listing with a placement by imagery and then go and take and verify accurate GPS readings and use them, then the fact you used the aerial's location effectively as a placeholder is pretty irrelevant :P

 

Now, if you started with a sat placement, then went for GPS readings, but favoured sat location over GPS, especially without verifying that the imagery is perfectly aligned - that will most likely cause problems unless you're lucky. That sort of falls under that list of strategies quoted earlier for doing your best to take accurate readings with your GPS device when placing a cache.

 

Chronological process of taking readings by GPS or aerial imagery? Irrelevant.

Accuracy priority? Completely relevant.

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Check out this area. I just did a quick measurement in Google Earth, and the difference between the imagery and the Google road data is approximately 240 feet. Interestingly in this case, however, the imagery is actually aligned almost perfectly (confirmed by my GPS track logs); it's the road data that's misaligned.

Interesting. But yeah by my experience, satellite is far more often out of alignment than road data. Neither is guaranteed to be accurate, but it's generally safer to trust road positioning over aerial. And as demonstrated by your point, it's typically very easy to determine if something is out of alignment, usually within a tile or two (either map source).

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And as demonstrated by your point, it's typically very easy to determine if something is out of alignment, usually within a tile or two (either map source).

Yes, and if you know how something is misaligned you may be able to correct for it, but it won't always be easy to determine that. In my case, the imagery was pretty accurately aligned. What if it wasn't? That is, if the road data doesn't match the satellite imagery, what if both are wrong? The only way to determine that is by GPS. I had originally assumed that it was the imagery that was wrong in the area I linked to, and it wasn't until I overlaid a GPS track log that I realized it was the other way around.

Edited by The A-Team
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Geocaching has evolved since I started. I don’t care if the location is somewhat off, in fact I enjoy looking around for where the geocache could possibly be hidden. It would take some of the fun out of it if the coordinates were always spot on. If you’re all about numbers, I can see where slightly off coordinates could be an issue (I'm glad I'm not about numbers :rolleyes: ). If the coordinates are too far off your logs will reflect this and you can make corrections. Let’s not overcomplicate things or the game becomes no longer enjoyable.

Edited by TahoeJoe
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So where is this one? (in Chrome) Link

 

Note: if you use IE the imagery will be different and you won't see the issue.

Probably somewhere out on that pipeline, likely without permission. :laughing:

 

BTW, I looked at it in IE and see the break in the imagery alignment just fine. The difference won't appear or disappear depending on the browser, it will be whether you're using the new or classic Google Maps. In this case, the problem is only present in the new Google Maps.

 

Edit: That does raise another point. Just because the alignment may appear accurate when looking at a spot on the map at home, it isn't guaranteed that your app will be using the same imagery and may not be as accurate.

Thanks, hadn't realized I was using different versions of Google Maps. Somewhere nearby there is (or was) a footbridge that was similarly mis-stitched. Couldn't find it upon quick inspection ...

 

Anyway, point being ... if one hasn't seen similar stitching errors in mapping products, it's worthwhile to note. They do happen.

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And as demonstrated by your point, it's typically very easy to determine if something is out of alignment, usually within a tile or two (either map source).

Yes, and if you know how something is misaligned you may be able to correct for it, but it won't always be easy to determine that. In my case, the imagery was pretty accurately aligned. What if it wasn't? That is, if the road data doesn't match the satellite imagery, what if both are wrong? The only way to determine that is by GPS. I had originally assumed that it was the imagery that was wrong in the area I linked to, and it wasn't until I overlaid a GPS track log that I realized it was the other way around.

 

Yup, which is why you, really, should always start with GPS coordinates, until you can determine that they're not as potentially accurate as the satllite imagery (more often than not it'll be sufficient at that point), and if everything is off, well, you're pretty much screwed :P Either disclaim of all the difficulty on the cache page and drop a hint, or just don't put a cache there :)

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This is just a friendly reminder for COs to verify the exact coordinates of their caches using Google maps imagery when possible.

Let's face it - using smartphones is often the way caching is done these days, so COs (including myself) get coordinates with their caching app's compass. While there's no issue with this method of getting coordinates, it may be less accurate than using a conventional GPSr. So it becomes even more important to verify the location of the coordinates on Google maps or similar imagery in order to ensure accuracy. I only have four hides but I've had to make adjustments based on seeing the coordinates from my app didn't line up on the map with where I knew the cache was.

What made me think of this issue was trying to find a cache a few days ago and logging a DNF bc I came up empty.

Today I came back and used my geosenses and expanded my search area. I know, I know, I should have done this in the first place. BUT the imagery on the app clearly showed the cache location on one side of a gravel road when the true location ended up being on the opposite side of the road. That's my beef - especially with urban caching (but of course not limited to urban caching) we as COs need to make sure our cache coords are accurate to the digital map.

To me, achieving coordinate accuracy gets to the essence of geocaching - finding a container based on GPS location.

 

Hi. I want to apologize for the unintended rudeness of my fellow geocachers here and extend a warm welcome to you for recently joining this exciting hobby.

 

Welcome to Geocaching!

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So where is this one? (in Chrome) Link

 

Note: if you use IE the imagery will be different and you won't see the issue.

Note: You'll only see the issue if using the new Google Maps, and not Google Maps classic. Thanks The A-Team for the clarification.

 

I had another image that I've posted a few times when the question of using satellite imagery showed up but the images have been updated so it's less of an issue. In that case, it was a cache that I found in Costa Rica along a long twisty road in between San Ramon and La Fortuna. The arial view of the area was almost entirely covered in clouds (that's what happens in a rain forest) and looking at the image there would be no way to tell if the cache was on top of the steep cliff there or down near the river below.

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Alternatively, one can use the 'map' view and still use gps - I cannot stand the distance and bearing view :P I vastly prefer looking at the overhead view with my location in relation to the target pin (and afaik, most every device offers this ability); regardless of the map being used. There's no tradeoff in accuracy in that context, it's just a different angle, really, on the same data. If you see your location an inch from the GPS waypoint from above, the distance and bearing view will technically indicate exactly the same information, just in a numerical format.

 

I like seeing 'the bigger picture', as it were. My location, plus the accuracy bubble, plus the target waypoint. That's where it's at. Visual representation of digital numbers. :laughing: If I really want I can still turn on rotation so I can either see the direction I'm currently facing, or the map can rotate (again two ways of depicting the same thing). But typically, just my location visually represented with the target wpt has always been sufficient (and watching how my location moves as I bear down on the target; I might turn on the compass if I still have difficulty).

 

And again, that's not the same as navigating by aerial imagery. It's just another (graphical) view of GPS data.

 

ETA: But this doesn't have to do with hiding, since there's no pin already available for where the cache, which you're going to place, is. :P So... sort of irrelevant to the OP, heh

Edited by thebruce0
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Alternatively, one can use the 'map' view and still use gps - I cannot stand the distance and bearing view :P I vastly prefer looking at the overhead view with my location in relation to the target pin (and afaik, most every device offers this ability); regardless of the map being used. There's no tradeoff in accuracy in that context, it's just a different angle, really, on the same data. If you see your location an inch from the GPS waypoint from above, the distance and bearing view will technically indicate exactly the same information, just in a numerical format.

 

I like seeing 'the bigger picture', as it were. My location, plus the accuracy bubble, plus the target waypoint. That's where it's at. Visual representation of digital numbers. :laughing: If I really want I can still turn on rotation so I can either see the direction I'm currently facing, or the map can rotate (again two ways of depicting the same thing). But typically, just my location visually represented with the target wpt has always been sufficient (and watching how my location moves as I bear down on the target; I might turn on the compass if I still have difficulty).

 

And again, that's not the same as navigating by aerial imagery. It's just another (graphical) view of GPS data.

 

ETA: But this doesn't have to do with hiding, since there's no pin already available for where the cache, which you're going to place, is. :P So... sort of irrelevant to the OP, heh

 

Veering slightly off topic...

 

...but I find the map view is only valuable until one is a few hundred feet from GZ. Once I get within maybe 200 to 300 feet, the icon representing me begins to overlap the icon representing the cache...at which point I switch to the compass view. Map views, for me, are only a navigation tool...not a tool for pinpoint accuracy. Compass views offer only a slightly finer degree of accuracy and allow me to keep from having to look at the screen as much.

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