Placing caches with Just Google Earth and compass

[+narcissa]

 

 

With some of these people out there I would love for someone to use goggle map off by 150 ft or even 60 because they don't take multi readings. Plus why do you need a GPS I known a couple of people that use only maps plus goggle is pretty dadgum close on the coords

 

150 < 60 ?

 

Anyway... if a cache is off by 150 feet, there's more to the problem than just failure to take good readings.

[+NeecesandNephews]

With some of these people out there I would love for someone to use goggle map off by 150 ft or even 60 because they don't take multi readings. Plus why do you need a GPS I known a couple of people that use only maps plus goggle is pretty dadgum close on the coords

 

 

 

That is just hard to read.

 

If I found a cache that was 150 ft off the coords, I would log a SBA without a blink. And if you are referring to taking multiple readings on google maps to list your new cache you are wasting your time.

 

No one said you need a GPS to hunt. Everyone has said you need one to hide. Including Groundspeak.

Edited March 14, 2010 by NeecesandNephews

[+narcissa]

 

 

 

That is just hard to read.

 

 

IAWTC

[Dj Storm]

...

When I said [Google Earth is] safe to use I should have specified that I meant generally safe for personal navigation, not for placing caches. For the most part I understand and accept the argument against placement with just the tools I use now. Still to satisfy my own curiosity I am still going to try to borrow a GPSr and do a confirmation of the cache and a wider confirmation of GE using recognizable landmarks, as like I said my methods have produced sub meter accuracy in the past and as well I'd like to get a better idea of the limits of the tools I use.

...

 

Please look at this cache: GC1PMXZ

 

Here is a screenshot from Google Maps:

 

The cache, according to GPSr readings, is placed where the container indicates. If you use the satellite view, the container is at the tip of the "1" green arrow, 64 meters (210 feet) off. If you use the map view, the placement is where the "2" arrow indicates, 143 meters (468 feet) off from the GPSr coordinates.

This might be an extreme case, from a place where accurate imagery is not available, but it shows that it can happen.

[+edscott]

I'm confused by your post. Is the actual placement of the cache in the green area beside the building at the intersection of Golsti and Nicolae Simache that is obscured by the traditional cache icon? ..or is it at one of your green arrows? If I understand your first sentence correctly the satellite image is fine. It's obvious the map overlay is out of registration.

[+dfx]

I'm confused by your post. Is the actual placement of the cache in the green area beside the building at the intersection of Golsti and Nicolae Simache that is obscured by the traditional cache icon? ..or is it at one of your green arrows? If I understand your first sentence correctly the satellite image is fine. It's obvious the map overlay is out of registration.

the "actual" placement depends on which part of the map you look at. the aerial image is offset from the map (the street lines and names), and both are offset from where they should be, that's why there's three cache "locations".

 

if you look at the aerial image, the cache is located at the "1" arrow, which appears to be in a tree along Bulevardul Independentei, just north of the angled intersection with Strada Golesti (hope i read that right). however you don't see the street name there, because the street line with the name appears further to the left - if you go by this, the cache is located at the "2" arrow. and the cache icon is where the actual coordinates are.

 

if you shift the aerial image including the "1" arrow over so that the "1" arrow overlaps with the cache icon, then the aerial image would be aligned correctly. if you then also shift the street map including the "2" arrow over so that the "2" arrow overlaps with the cache icon, then map would be properly aligned as well.

[+Highland Horde]

just my $.02 ... a week or so ago i was looking at a place for a new cache, there was a multi not too far away that I hadn't done so I went on google earth and got the coords of where I was going to place the cache and email my reviewer to see if the area was clear. He gave it the ok and I want out and placed the cache with my GPSr. While I was placing i looked at the coords I sent to the reviewer...they were darn close to the middle of a lake ... I got a couple good readings on the actual placement and submitted it with no problems....It worked out good for me...saved me from making an extra trip out if it wasnt an ok location but after seeing how far off the coords can be on google earth I would never place without a dedicated GPSr...personally I wouldnt place a cache with a GPS enabled phone either (my blackberry doesnt seem to be a accurate....good enough to find but nit to hide) but that is just me...

[+dfx]

personally I wouldnt place a cache with a GPS enabled phone either (my blackberry doesnt seem to be a accurate....good enough to find but nit to hide) but that is just me...

it should be ok if you let it average long enough. we're using a PDA for caching which partly has the same problems (the GPS chip is good but the builtin antenna is bad), so when we place a cache i usually connect an external antenna to improve reception and accuracy, but occasionally we don't have it with us, in which case i let it take a lot of samples for averaging (read 500+), and people were still reporting spot-on coordinates.

 

the nice thing about the GPS software we're using is that it's reporting the standard deviation while averaging the samples, which gives a pretty good estimate of how accurate the readings are. in most cases it's showing a number around 4-5 meters, which exactly corresponds to the HDOP values i see in the best cases (0.9 or sometimes 0.8). if it's showing a standard deviation of 15 or 20 meters or even more while averaging, chances of ending up with bad coordinates are pretty high.

Edited March 16, 2010 by dfx

[+TheAlabamaRambler]

Since I upgraded my home PC network to 64-bit Windows 7 Ultimate Google Earth won't run on my system, but up until then (3 months ago) Google Earth showed the coordinates for my house about 600 feet up the street from its actual location.

 

This made it particularly interesting since the GPS-recorded coordinates for the cache on my front porch showed up a block away from where Google Earth thought my house was!

 

For a few of the events I hosted last year I got the coordinates for the restaurant or wherever it would be held from Google Earth rather than going there and getting them with my GPS. They were always so far off, in one notable case by a mile and a half, that I quit trusting Google coordinates for anything.

 

Anyhoo, even if they have fixed those issues, the fact that the Guidelines require the use of a GPS to get accurate coordinates for a hide make the whole subject moot.

[avroair]

I've been geocaching for less then a month and have found quite a few of them using just maps, Google Earth and a compass (I don't own a GPSr and am not planning to buy one) and today I came across one that was about 16 meters off of its posted coordinates.

 

I determined this using the Google Earth ruler tool and a bearing shot from a landmark only 25 meters from the cache with my compass while at GZ and it got me thinking that I could definitely place caches to within ~1 meter accuracy with just Google Earth and a compass, provided there were some landmarks visible from Google Earth near the cache site. I'm hoping I could peoples input on this method!

 

First off the guidelines require the use of a GPS

You as the owner of the cache must visit the site and obtain the coordinates with a GPS. GPS usage is an essential element of geocaching. Therefore, although it is possible to find a cache without a GPS, the option of using accurate GPS coordinates as an integral part of the cache hunt must be demonstrated for all physical cache submissions.

 

Secondly the maps from Google may or may not be correctly aligned. Your estimated position might be off by quite a bit.

 

I think what you are talking about is called orienteering.

[+HeliDood]

 

Someone also alluded to problems with Google Earth not being properly geo referenced, does anyone have examples of this? I know that imagery age can certainly be a problem, but I haven't been in a situation yet where I've felt the geo referencing was actually off.

 

I've found that the satellite imagery in GE isn't quite to scale, its only an approximation. In Google Earth, find a landmark with known distances and use the ruler tool to see for youself.

 

Find a football field. The distance between Goal line to Goal line should be exactly 100 yards.

Find a baseball field. The distance between bases should be 90 feet. How far is it from home plate to center field? Right field?

 

In GE, I've found several instances where distances aren't what they're supposed to, sometimes off by as much as 10%

[+Markwell]

Find a football field. The distance between Goal line to Goal line should be exactly 100 yards.

Find a baseball field. The distance between bases should be 90 feet. How far is it from home plate to center field? Right field?

 

Soldier Field, Chicago - goal to goal 99.57 yards (1.5 feet off)

Qwest Stadium, Seattle - goal to goal 100.28 yards (9 inches off)

Cellular Field, Chicago, home of the White Sox - Home to First 87.5 feet (2.5 feet off)

I guess we're lucky around here.

 

But I still wouldn't suggest using it.

[+moose61]

Two years ago there was a cacher in the neighbourhood who did hide caches using Google Earth. The were never accurate enough, always a nightmare. All cachers hated his caches. At the end all of his caches were archived by the reviewer and the cacher was not allowed to place any caches any more until he had a GPSr.

 

My recommandation: keep the fun in the game. Use the assistance of an fellow geocacher or don't place a cache. You will get the most joy of your cache if you read that other like your cache.

[+blb9556]

I found 30 caches using only maps. It was tough compared to my Garmin Oregon now!

[+edscott]

Two years ago there was a cacher in the neighbourhood who did hide caches using Google Earth. The were never accurate enough, always a nightmare. All cachers hated his caches. At the end all of his caches were archived by the reviewer and the cacher was not allowed to place any caches any more until he had a GPSr.

 

My recommandation: keep the fun in the game. Use the assistance of an fellow geocacher or don't place a cache. You will get the most joy of your cache if you read that other like your cache.

 

I agree with your final statement. That's why I place caches. I do question whether your subject's poor coordinates were because he used Google Earth, or because he didn't know how to use Google Earth.