A silly question on GPS coordinate formats...

[BFG99]

Purely out of curiosity: which GPS coordinate format do you tend to use when entering new caches on the website, or importing into your GPS unit?

 

There are several options:

DDD MM.MMM -- the main format used by this website. Gives information to about 73 inches (in my latitude, central MN).

DDD.DDDDD -- used by this website's maps. Gives information to about 44 inches.

UTM -- alternate given by this website. Gives information to about 39 inches.

DDDD MM SS.SS -- A popular alternative. Gives information to about 12 inches.

 

It may be a moot point, since many GPSs are only accurate (in nominal conditions) to within +/- 8 feet. But, I'd prefer to enter whichever coordinates are going to get me closest to the find, which usually means using the same format that the person entering it used, instead of converting. So, what type do you usually use?

[+cerberus1]

"Tend" to use? Is it different elsewhere?

We've used, the site uses, our GPSrs use WGS84 since we started.

[+HHL]

"Tend" to use? Is it different elsewhere?

We've used, the site uses, our GPSrs use WGS84 since we started.

 

WGS84 is a datum - not a format.

Edited April 7, 2016 by HHL

[+dprovan]

The only time I use anything other than DD MM.mmm is when I'm forced to by a puzzle.

[BFG99]

Yep, it's clear that WGS84 is the way to go for the datum, specifically the EGM96 (revision 2004) version. This is purely about coordinate systems within the datum.

[+lee737]

The only time I use anything other than DD MM.mmm is when I'm forced to by a puzzle.

 

+1

I wouldn't worry about the theoretical resolution of each of the formats, in practice none will ever be that accurate.....

Also - converting to a higher resolution format won't improve the accuracy of the lower resolution value.

 

Edited April 7, 2016 by lee737

[+cerberus1]

Thanks hhl, going by memory (and fading a bit I guess )

In Groundspeak's Glossary of terms:

"WGS84

The most current geodetic datum used for GPS is the World Geodetic System of 1984 (WGS84). The significance of WGS84 comes about because GPS receivers rely on WGS84. Geocaching uses the WGS84 datum by default. We also use the coordinate format HDDD MM.MMM, which is a standard for handheld GPS receivers. HDDD means Hemisphere and degrees. MM.MMM are minutes in decimal format. It is critical that the format be correct, otherwise geocachers will be unable to find your geocache."

[+Harry Dolphin]

There are several options:

DDD MM.MMM -- the main format used by this website. Gives information to about 73 inches (in my latitude, central MN).

DDD.DDDDD -- used by this website's maps. Gives information to about 44 inches.

UTM -- alternate given by this website. Gives information to about 39 inches.

DDDD MM SS.SS -- A popular alternative. Gives information to about 12 inches.

 

It may be a moot point, since many GPSs are only accurate (in nominal conditions) to within +/- 8 feet. But, I'd prefer to enter whichever coordinates are going to get me closest to the find, which usually means using the same format that the person entering it used, instead of converting. So, what type do you usually use?

 

Precision versus accuracy. Precision is worthless without accuracy. They all come down the accuracy of your GPSr, and the satellites.

[+Mineral2]

When I'm not geocaching, IE I'm out collecting positional data where I need to make calculations such as distance, area, angle, etc. I use the UTM format because it adheres to a 1m x 1m grid. The equality of the axes makes it real nice to perform geometric calculations over relatively short distances. I mostly convert to UTM once I'm back at the computer. I really only need precision down to the nearest meter. Beyond that, it's a little silly.

[+fizzymagic]

When I'm not geocaching, IE I'm out collecting positional data where I need to make calculations such as distance, area, angle, etc. I use the UTM format because it adheres to a 1m x 1m grid. The equality of the axes makes it real nice to perform geometric calculations over relatively short distances.

 

As long as you don't care about north being the actual north, that is.

 

But yes, over distances on the order of a hundred meters or so it is useful for things like area, though it would be too inaccurate for anything much larger.

[+Mineral2]

UTM is great for finding your location on a 7.5 minute topo quad.