Google Maps Frustration

October 30, 2006

I've been trying to get a new geocache listed and my reviewer insists on relying in Google maps arial photos to confirm my caches location. My cache is in an residential area, in a small park. When you use google maps with my coords, the area google shows my cache to be is always on a rooftop or in a driveway. therefore my cache does not get published.

I'm not upset with my reviewer, he is just trying to do his job. What upsets me is the accuracy of google maps. I have tried three times to get coords that google agrees with an so far no luck.

Any suggestions?

October 30, 2006

I've been trying to get a new geocache listed and my reviewer insists on relying in Google maps arial photos to confirm my caches location. My cache is in an residential area, in a small park. When you use google maps with my coords, the area google shows my cache to be is always on a rooftop or in a driveway. therefore my cache does not get published.

I'm not upset with my reviewer, he is just trying to do his job. What upsets me is the accuracy of google maps. I have tried three times to get coords that google agrees with an so far no luck.

Any suggestions?

Try telling him that you have permission to put it on the roof

Seriously, try another service (like Yahoo or Terraserver) and see where the coordinates put you on their photos. If all three agree, your coordinates may be off. If they don't agree, send a link to the reviewer to the service(s) that show the correct location. And then keep track of people logging your cache -- if some start reporting that the coordinates are off, recheck them.

Edited October 30, 2006 by adjensen

1.1k · October 30, 2006

google maps is generally pretty accurate.

how sure are you about your coords?

October 30, 2006

Find out (I don't know and I'm too lazy/busy to check) whether google uses WGS-84, NAD-83, or NAD-27. I have no idea. There is a site that allows you to convert from one to another. I just try them all to see what comes up... The website is http://www.jeeep.com/details/coord/ I find it very, very useful converting from degree decimel to UTM or min/sec for work in biology/botany.. Anyway, an idea perhaps...

October 30, 2006

If he's not using Google Maps, but rather, GOOGLE EARTH, he may be having problems because of the terrain. When terrain is added to the view, I find that the longitude and latitude have accuracy problems (especially with the Google Earth Geocaching component). If I change views, the geocaches will jump around on the map. They show up in different places with every view. Tell him to turn off the "terain" layer, and that may help him get a more consistent view.

2k · October 30, 2006

Try taking a photo of your GPSr at the cache site with a few shots of the area.

2.8k · October 30, 2006

google maps is generally pretty accurate.

For parts of Rhode Island, the Google Maps are accurate, but not the aerial photo portions. See this Hybrid view:

If you enter coordinates, the push pin shows up where it belongs relative to the road, but is offset 50'+ on the aerial view. If the review is looking only at the aerial view, and there is a similar offset, there's your problem.

Looks like Marysville, WA has the same problem:

Try sending your reviewer a copy of the hybrid view.

(Edited for second image)

Edited October 30, 2006 by BBWolf+3Pigs

October 31, 2006

I've sent the reviewer a screenshot of the hybrid view of the cache area, which shows the streets being about 50 feet off where the aerial photo shows them. I also put an arrow pointing out my cache. I offered to send a photo of my gps display at the cache site as further proof.

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

October 31, 2006

I've sent the reviewer a screenshot of the hybrid view of the cache area, which shows the streets being about 50 feet off where the aerial photo shows them. I also put an arrow pointing out my cache. I offered to send a photo of my gps display at the cache site as further proof.

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

if anyone has any doubt about them being off, pull up there house on google earth, look at the coordinates they show for your residence, turn on your gps if the 2 arent several block s off at a minimum, shot me a note so i can retract this, mine dont even come close

2.8k · October 31, 2006

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches.

Well, that's silly. If Google's aerial shots are inaccurate, you should not be penalized for your cache placement! What are you expected to do..change your coordinates to make a few people's lives easier? I've learned to compensate for the 50-100' offset in Rhode Island when viewing aerial shots in Google Maps. People elsewhere should as well. And worse comes to worse, add a note that it's not on the roof (or driveway or whatever).

And remember it's "Geocaching - The Official Global GPS Cache Hunt Site"...it's not the "Google Maps Hunt Site".

Edited October 31, 2006 by BBWolf+3Pigs

October 31, 2006

I could see the reviewer using Google Maps to check the aproximate location, but not the exact location. If he does that with every cache, would be surprised to see many caches in your area.

Make sure you also forward your reviewing a link to this thread.

Don't know if its possible, but you may want to ask if it's possible to have a different reviewer give his opinion on your cache.

3.2k · October 31, 2006

I've found google maps to be "fairly close" but not really accurate. For instance I had an "unlisted" cache come up on our local caching forums one day. A local cacher who is a police officer was celebrating getting off of his traffic rotation and placed an unlisted cache consisting of an official traffic cop stainless steel coffee mug. I was at work and pulled it up with google maps. I took a short "leave" from work and looked for the cache. I couldn't find it. After half an hour I decided to expand my search and found it a full block away from where google maps showed it. As for google earth...... don't even get me started about the horrid accuracy there.

5.3k · October 31, 2006

I've sent the reviewer a screenshot of the hybrid view of the cache area, which shows the streets being about 50 feet off where the aerial photo shows them. I also put an arrow pointing out my cache. I offered to send a photo of my gps display at the cache site as further proof.

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

I've seen an area in Indiana where the Google Earth photos are off by about 50' (right, ElementalJay?).

October 31, 2006

Well, based on info that some of the posters supplied in this thread, I was able to plead my case to the reviewer and get my cache published.

It will be interesting to see what happens when people start to look for my cache. Hopefully my coords are spot on and there is not some weird atmospheric anomaly in the area.

Thanks!

2.8k · October 31, 2006

Well, based on info that some of the posters supplied in this thread, I was able to plead my case to the reviewer and get my cache published.

It will be interesting to see what happens when people start to look for my cache. Hopefully my coords are spot on and there is not some weird atmospheric anomaly in the area.

Thanks!

Congrats! I'm guessing it is on the playground (?) side of the fence.

October 31, 2006

Since I was in the area today, I decided the best way to check your coordinates was to grab the FTF on the cache. Your coordinates are just fine. I showed 18 ft. at the cache and trust me, I was not on anybody's roof.

You're right Google Maps suck for this area. :laughing:

November 1, 2006

I've sent the reviewer a screenshot of the hybrid view of the cache area, which shows the streets being about 50 feet off where the aerial photo shows them. I also put an arrow pointing out my cache. I offered to send a photo of my gps display at the cache site as further proof.

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

if anyone has any doubt about them being off, pull up there house on google earth, look at the coordinates they show for your residence, turn on your gps if the 2 arent several block s off at a minimum, shot me a note so i can retract this, mine dont even come close

Where I live - the house on Google is just a blob - you do good to find the block:)

In my humble opinion - this is bull, Geocaching was started with the intention of using a GPSr.

When it started none of the online maps were worth a crap, Google Earth didn't exist and anyone attempting to cacher used a GPS.

If the reviewer has this attitude I think it needs adjusted.

1.1k · November 1, 2006

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

that's just silly.

glad your cache was published. hope it's a good one. :laughing:

November 1, 2006

I've sent the reviewer a screenshot of the hybrid view of the cache area, which shows the streets being about 50 feet off where the aerial photo shows them. I also put an arrow pointing out my cache. I offered to send a photo of my gps display at the cache site as further proof.

The reviewer noted that there are users who don't have or use a GPS and rely on services like Google maps to find caches. If google, and possibly other online map services are that inaccurate with their aerial views, shouldn't such activity be discouraged?

if anyone has any doubt about them being off, pull up there house on google earth, look at the coordinates they show for your residence, turn on your gps if the 2 arent several block s off at a minimum, shot me a note so i can retract this, mine dont even come close

Interesting. I got curious and plugged in my home coordinates. The satellite view is right on the money. The arrow is still correct on the hybrid view but the streets are offset so the arrow is on the superimposed view of the street (Google's idea of where the street is?).

6.7k · November 1, 2006

Maybe it varies by area, I don't know - I do know that if I enter my home coords I get an excellent hi-res photo with perhaps 5' accuracy of where I was standing in the back yard when I shot the coords! You can see the brick BBQ firepit I was standing by!

I recently placed a cache using Google Earth to shoot the coordinates from home first, wrote the listing, then went and placed the cache. Unedited the coords are less than 15' off the place where I actually went and hid the cache the next morning!

I was showing Google Earth to a friend last week, looked at a few caches, all were spot on!

If you look at any of the caches in my area GE will show you right where to go, you won't need a GPS!

A friend called me last night for help finding a new cache. Based on the clue (between two trees 45' West of a particular mark) I was able to guide her to the cache from 60 miles away using GE! The hint was wrong - the trees were South of the mark!

Look at cache Bird Sanctuary, for example. It not only shows it to be at the base of a power tower, it shows you which leg it is near!

I suspect that most Reviewers use multiple maps and tools, but al least in my area GE looks fine to use.

Ed

Edited November 1, 2006 by TheAlabamaRambler

November 1, 2006

I suspect that most Reviewers use multiple maps and tools, but al least in my area GE looks fine to use.

Ed

There are also areas close to me where Google maps are very accurate as well. It was only when I placed this most recent cache that I discovered just how inaccurate they can be in some locations. I would have never predicted that much inaccuracy. Perhaps it has something to do with the curvature of the Earth and that the photos are flat and that makes the areas at the edge of the photo be less accurate or some other strange reason - who knows.

Anyway - if anyone is reading this who is thinking of relying on aerial view google maps, don't put too much faith in them. They only serve as a guide, and are not meant to have the accuracy required for sending a guided missle down someones chimney or even geocaching.

JaySTE

5.3k · November 1, 2006

It definitely varies by area. The reality is that, contrary to the obnoxious song, it's NOT a small world. Marching a plane around the planet, taking pictures, and aligning those pictures to known points (georeferencing) and making them computer accessible is a hard and expensive problem.

In some spots, they'll be spot on. In some, as in the images earlier in this thread, there will be a clear shift. Here is a similar example that I used in a response to a similar question in the Google Earth forum. I don't know if the Navtech layer is off or the imagery layer is off, but from the problem report, I'm guessing it's the imagery layer in that case. It's a variation of the "A man with two positioning technologies never knows where he is" problem.

It's not hard to find cases where the individual tiles have different skews which results in the maps having discontinuities in roads. It's like someone tore the map and taped it together, but didn't quite get it lined up right. You can even see odd cases of three different resolutions and/or generations of data used in the same area.

The offset of any individual tile is not a constant and may in fact even vary from day to day as they're constantly buying new imagery and tweaking the offsets of the existing and collected imagery. If you want to fix the problem at the source, file a report at

http://bbs.keyhole.com/ubb/postlist.php/Ca...ard/SupportData

In short, the imagery is typically accurate enough that a reviewer can question the type of hide ("why does your cache require scuba gear when your coords put it in the Mall of America?") but relying on the accuracy imagery of more than a few dozen feet is just unwise.

6.7k · November 1, 2006

Interesting!

I reported earlier that the coords were spot-on for my home.

In playing with it just now I noticed that is true if I enter the coords to look for, but not if I enter my address.

A search on my mailing address puts me 6 houses (about 400') west of mine!

Ed

5.3k · November 1, 2006

The accuracy of geocoding (converting an address to coords) is a different problem than one of aligning imagery, Ed.

GPSes (indeed, computer maps) don't have measured coords for every street address. They have coords for 1000 main street and they have coords for 1400 main street. 1200 main street is assumed to be about halfway between them. 1300 halfway between those. There are a few rare cases (high rise towers, with adjacent parking lots, etc.) where an adjustment will be made but in most cases, it's a straightforward linear thing.

If you're in a land where the number of mailboxes is constant and the lot sizes are all the same, it all works very well.

Of course, that happens approximately never. So the GPS will get you within the right block or so and in the end, you actually have to look for the mailbox number or the hotel or whatever it is that was geocoded.

7.4k · November 1, 2006

In short, the imagery is typically accurate enough that a reviewer can question the type of hide ("why does your cache require scuba gear when your coords put it in the Mall of America?") but relying on the accuracy imagery of more than a few dozen feet is just unwise.

At the same time, if a cache shows up as on the roof or driveway of a house, it is reasonable for the admin reviewing the cache to question it. After doing this for 6 years, I have to say that it is more often the case that the coords are wrong than the aerials, at least when talking about the high-detail urban aerials in my area.

Looking at the cache that started this thread, I think that both the cache owner and the reviewers made the right choices. The coordinates were questioned, the cache owner adjusted them, the coordinates were again questioned (they moved from roof to driveway), and then the cache owner confirmed them again. The reviewer then posted the cache.

November 1, 2006

FWIW, so far I've found 2 caches using just Google Maps and no GPSr. I looked up the cache at work, recognized the area and found them. Granted, they were 1/1 parking lot caches, but the green arrow pointed right at GZ.

November 1, 2006

FWIW, so far I've found 2 caches using just Google Maps and no GPSr. I looked up the cache at work, recognized the area and found them. Granted, they were 1/1 parking lot caches, but the green arrow pointed right at GZ.

Based on the what we have seen on this thread, it doesn't look like you will always be so fortunate. Google Maps are great but not perfect.

5.3k · November 1, 2006

At the same time, if a cache shows up as on the roof or driveway of a house, it is reasonable for the admin reviewing the cache to question it. After doing this for 6 years, I have to say that it is more often t

I agree that a round of "are you sure" is warranted. Digits get swapped, folks mark coords with crummy satellite fixes, and stuff gets misentered all the time.

In case it helps the admins, turning on hybrid mode usually (not always) helps highlight this problem. (Those that build tools for such things will find the "t=h" option in the URL handy...)

November 1, 2006

Where I live - the house on Google is just a blob - you do good to find the block:)

In my humble opinion - this is bull, Geocaching was started with the intention of using a GPSr.

When it started none of the online maps were worth a crap, Google Earth didn't exist and anyone attempting to cacher used a GPS.

If the reviewer has this attitude I think it needs adjusted.

The hobby, in other forms and names has been around a lot longer then GPS systems.

Paper maps, compass, sextant, and a good watch. :blink:

If the cache in question is GCYR4Y, I put the numbers into a program that uses images from Teraserver and I get it in some trees 2.3 miles east of the center of down town, 364 feet north of a road and 230 feet west of what looks like a walking or bike trail. And just over 1400 miles from my place.

Edit: Got the east and west switched. :huh:

_____________

Andre' B.

Edited November 1, 2006 by Andre' B.

7.4k · November 1, 2006

In case it helps the admins, turning on hybrid mode usually (not always) helps highlight this problem. (Those that build tools for such things will find the "t=h" option in the URL handy...)

Perhaps, although I find the vector road data to be incorrect more often than the aerial imagery.

November 1, 2006

If the reviewer has this attitude I think it needs adjusted.

I should make it clear that in my case at no time did I feel that my reviewer needed an attitude adjustment. He was very professional about the whole thing and in the end it was an educational experience for both of us.

November 1, 2006

jaySTE, team tettamanti have the same avatar, just sayin...

November 1, 2006

jaySTE, team tettamanti have the same avatar, just sayin...

I had it first! :blink:

November 1, 2006

The hobby, in other forms and names has been around a lot longer then GPS systems.

Paper maps, compass, sextant, and a good watch.

_____________

Andre' B.

A hobby - but not THIS hobby.

http://www.geocaching.com/about/history.aspx

Officially started on On May 3, 2000 - letterboxing and all the other "things" really are not part of it.

BTW - I've been at it since June 01.

Google Maps Frustration

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