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on line vs paper maps


stephenf64

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Being a newcomer to caching but not hiking, I have always relied on a map and compass. When hiding caches I try to verify their positions with online maps such as google maps, google earth or Bing. I am finding, though, that often the co-ordinates don't match and can on occasions be miles out. I have just had to disable a cache because when I posted it my co-ordinates did not match google maps and I trusted google, only to be told that the co-cordinates are way off. My question is, why do these discrepencies occur and which should I trust more, online or paper maps.

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Being a newcomer to caching but not hiking, I have always relied on a map and compass. When hiding caches I try to verify their positions with online maps such as google maps, google earth or Bing. I am finding, though, that often the co-ordinates don't match and can on occasions be miles out. I have just had to disable a cache because when I posted it my co-ordinates did not match google maps and I trusted google, only to be told that the co-cordinates are way off. My question is, why do these discrepencies occur and which should I trust more, online or paper maps.

 

Link for reference (PDF file format):

 

How accurate is Google Earth?

 

The article is several years old, but I believe it's still applicable to online map data in general, and the shortcomings of relying on the maps as a sole resource for coordinate data.

 

That being said, there are some places in my area where it's difficult/impossible to get a good satellite signal, and I sometimes use online maps to double check the coordinates I got at the cache site. Failing that approach, I usually fall back on giving a descriptive Hint to help people locate the cache.

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I wouldn't trust googlemaps (Or the others) especially with satellite imagery. That can be WAY off!

I find it varies by area. Here, most of the time, it's pretty good - I almost always use just mapping (and generally google sat images) to find caches and in this area things are very reliable. But in other areas (and on odd occasions at the edges of imagery sets) I've noticed less reliability certainly.

 

Once you know the reliability of the general area I think you can then make a judgement as to whether or not the tool is reliable or not.

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I wouldn't trust googlemaps (Or the others) especially with satellite imagery. That can be WAY off!

I find it varies by area. Here, most of the time, it's pretty good - I almost always use just mapping (and generally google sat images) to find caches and in this area things are very reliable. But in other areas (and on odd occasions at the edges of imagery sets) I've noticed less reliability certainly.

 

Once you know the reliability of the general area I think you can then make a judgement as to whether or not the tool is reliable or not.

 

Using the images to Find a cache is one thing.

When the Guidelines state:

 

Listing Guidelines for All Geocaches

 

Technical Requirements

Listings must contain accurate GPS coordinates.

 

You must visit the cache location and obtain the coordinates with a GPS device. GPS usage is an integral and essential element of both hiding and seeking caches and must be demonstrated for all cache submissions.

 

You really should be using a GPS of some description, and not maps/images on the internet.

 

For the OP.

When taking coordinates, check you have the correct Datum set, and take your time to let your device settle, before reading the coordinates.

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Using the images to Find a cache is one thing.

When the Guidelines state:

 

Listing Guidelines for All Geocaches

 

Technical Requirements

Listings must contain accurate GPS coordinates.

 

You must visit the cache location and obtain the coordinates with a GPS device. GPS usage is an integral and essential element of both hiding and seeking caches and must be demonstrated for all cache submissions.

 

You really should be using a GPS of some description, and not maps/images on the internet.

I think the OP was only trying to use the sat imagery as a backup weren't they? To "verify" position?

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Using the images to Find a cache is one thing.

When the Guidelines state:

 

Listing Guidelines for All Geocaches

 

Technical Requirements

Listings must contain accurate GPS coordinates.

 

You must visit the cache location and obtain the coordinates with a GPS device. GPS usage is an integral and essential element of both hiding and seeking caches and must be demonstrated for all cache submissions.

 

You really should be using a GPS of some description, and not maps/images on the internet.

I think the OP was only trying to use the sat imagery as a backup weren't they? To "verify" position?

Nope he says map and compass

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I wouldn't trust googlemaps (Or the others) especially with satellite imagery. That can be WAY off!

I find it varies by area. Here, most of the time, it's pretty good - I almost always use just mapping (and generally google sat images) to find caches and in this area things are very reliable. But in other areas (and on odd occasions at the edges of imagery sets) I've noticed less reliability certainly.

 

Once you know the reliability of the general area I think you can then make a judgement as to whether or not the tool is reliable or not.

 

Thanks Bear and Ragged for the advice. Re-reading the post I think i should reiterate I do take gps readings at the GZ but always look to verify them before posting. It is here that I get different readings fron map or google. Sorry for the confusion.

Edited by stephenf64
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I wouldn't trust googlemaps (Or the others) especially with satellite imagery. That can be WAY off!

I find it varies by area. Here, most of the time, it's pretty good - I almost always use just mapping (and generally google sat images) to find caches and in this area things are very reliable. But in other areas (and on odd occasions at the edges of imagery sets) I've noticed less reliability certainly.

 

Once you know the reliability of the general area I think you can then make a judgement as to whether or not the tool is reliable or not.

 

Thanks Bear and Ragged for the advice. Re-reading the post I think i should reiterate I do take gps readings at the GZ but always look to verify them before posting. It is here that I get different readings from map or google. Sorry for the confusion.

 

Read the FTF's log...

Newish cacher, and doesn't give details about how far or which direction the coords are 'off' so it may be their fault. :unsure:

 

Is it a miss-read or a miss-key -numbers transposed- of the numbers somewhere?

The maps on the site, once you enter the coords are reasonably good.

(And, yes I check the site's map after I've typed, as a double check. :) )

 

Other options:

The site 'hiccuped' as you were entering the coordinates, so it's the site's fault! :laughing:

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I use google to confirm, but if it doesn't match up, I go back into the field armed with my coordinates (and perhaps also a google calculated alternative) to see if my GPSr takes me to the cache.

 

I can use google because it seems to match pretty well in my area (but watch out for the 45 degree views google will give you in some area, 'cuz the 45 degree views are always way off in my experience). But I do not take google's numbers over what my GPSr told me. If the map contradicts my GPSr, that just means I need to go back to GZ and try again.

 

Paper maps still exist? I'd forgotten. It never even occurred to me you could calculate coordinates from them.

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The vast majority of cachers use a handheld GPS to find caches. You should use one to place a cache. If you don't have one, I recommend you find a local caching partner that will loan you one or go out with you to verify trhe placement. Keep in mind the expectation is the coordinates be accurate to within 15-20 feet or so.

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