Utm -or- Longitude/latitude

[willyum]

Some sites I see use UTM and some use Longitudes and Latitudes. Is one better than the other? Why?

And is there an overall standard for the world that all countries agree on.

[Tahosa and Sons]

UTM'S are the way to go when you want to use a map. Just be sure of what datume you are using. And the GPS and Maps can talk to each other.

Lat & Long are good for long distances such as ships at sea or planes in the air, and is the format used by the frog.

[+Alan2]

Which sites use UTM that you're aware of?

[willyum]

Which sites use UTM that you're aware of?

This site (Geocaching.com).

All of the caches that I've seen here are in both formats. Take a second look. They are stacked, UTM on the bottom.

That's what made me ask.

[+Prime Suspect]

Internally, GPS units use WGS84, and simply convert the results to whatever datum you've requested. Geocaching.com, likewise, uses WGS84 as the primary format. UTM is shown, but it's simply a conversion from the WGS84 datum.

 

Unless you're working with a cache that has some specific requirement that calls for UTM, there's really not much of a reason to use it.

[Prof. Y. Lupardi]

When you are on land and working with paper maps then you will be very very happy to have a square grid on them. Measuring distances and the positions of things on the map is easy. So you use the local grid or the UTM grid.

Those grids are mostly metric but I have seen India maps with grids in surveyer feet. (not imperial feet).

[+sTeamTraen]

UTMs can be great for puzzle caches because you can generate some pretty random-looking numbers. Just remember that in UTM, the first number is longitude, not latitude!

[+geognerd]

I've had UTM work well for me when searching for benchmarks.

[+Night Stalker]

If you are using an older GPS that won't display out to the 3rd decimal then I have been told that UTM is the way to go. It will be more accurate than downloading the coordinate in WGS84 out to the 2nd decimal.

[+tozainamboku]

Once again - a thread where datum and coordinate format are confused.

 

datum is a mathematical model of the shape of the earth. Most importantly a datum gives the diameter of the earth at the equator and the amount the earth is flattened at the poles. Using different datums results in the same location on on the earth having different latitude and longitude. The same latitude and longitude using different datums will represent different locations on the earth. www.geocaching.com uses the WGS84 datum. Some other web sites and many paper maps use different datums.

 

coordinate format means there are several way to represent a location and is independent of the datum used. The most common formats are latitude/longitude and UTM. Addtitionally, latitude and longitude can be written different ways. The three common formats of latitude/longitude are decimal degress (dd.ddd), degrees and decimal minutes (dd mm.mmm) and degress/minutes/seconds (dd mm ss)

 

To answer the original post - looking for a cache it does not matter if you use UTM or lat/long. Some people like UTM because both the Easting and Northing are in meters. They may feel more comfortable using the flattened 2D grid of UTM to thinking in terms of spherical cooridates where conversion to distance requires trigonometry. This is also the reason why UTM is helpful in doing some puzzle and offset caches.

 

Both UTM and lat/long are used internationally. UTM is not defined for the polar regions. WGS84 is an internationally agreed on datum. Many countries have not updated their paper maps, however. Paper maps are likely to use a different datum. Many countries have their own datum (based on surveys done a century ago). In addition many countries have there own grids which are used instead of UTM. Many GPS units have capabilities to set to different datums and different coordinate formats (including some national grids). These settings effect the display and user interface on the GPS unit. Internally, the GPS always uses WGS84 datum and stores the location in lat/long.

[+LSUFan]

Tozainamboku gave a great explanation of some of the differences for the two coordinate formats. As far as one being better than the other, my opinion is the UTM system is much easier if you want to figure the distances between two points without having to do a lot of mathematics. It's all just straight adding and subtracting (as long as you stay within the same zones and bands of the UTM).

 

It's easier using UTM on paper maps in the field for this same purpose also. Once you understand how both formats work and the measurements for which they represent, you can use either system fairly well, but I still think UTM's are easier for the beginner-----as long as the metric system doesn't bother you.

 

I have written an explanation of these different formats in lesson stages for my local geocaching club and will be more than happy to email them to you if you like. It explains the numbers for both formats and how to read/convert them. If anyone didn't know what the zones and bands I referred to earlier, then you need these lessons.

 

I really believe everyone should know what these numbers mean. You can then impress your non-geocaching friends at parties. It beats card tricks.

[poshprimitives]

Tozainamboku gave a great explanation of some of the differences for the two coordinate formats. As far as one being better than the other, my opinion is the UTM system is much easier if you want to figure the distances between two points without having to do a lot of mathematics. It's all just straight adding and subtracting (as long as you stay within the same zones and bands of the UTM).

 

It's easier using UTM on paper maps in the field for this same purpose also. Once you understand how both formats work and the measurements for which they represent, you can use either system fairly well, but I still think UTM's are easier for the beginner-----as long as the metric system doesn't bother you.

 

I have written an explanation of these different formats in lesson stages for my local geocaching club and will be more than happy to email them to you if you like. It explains the numbers for both formats and how to read/convert them. If anyone didn't know what the zones and bands I referred to earlier, then you need these lessons.

 

I really believe everyone should know what these numbers mean. You can then impress your non-geocaching friends at parties. It beats card tricks.

 

thanks for the help could you email me the lesson on zones and such. I am so confused!!! candicemcmahon@comcast.net

Edited August 18, 2006 by poshprimitives

[+Alan2]

Some links:

Link 1

 

Link 2

[Middie08]

I really believe everyone should know what these numbers mean. You can then impress your non-geocaching friends at parties. It beats card tricks.

 

This happens to me at work all the time. Our mapping system (I'm a GIS manager for an electric/gas utility) uses UTM. When people ask, I always take the time to explain the projection to them along with the concept of datums. It usually results in nodding heads and blank stares, like I'm Capt. Kirk explaining how the warp drive on the Enterprise works. Sometimes people e-mail me with the need to know how to convert map files into our projection. When I tell them to use UTM Zone 16, NAD 27, Clarke 1866 elipsoid, in meters, they usually reply "If you could just do it and send it back....."

[poshprimitives]

I really believe everyone should know what these numbers mean. You can then impress your non-geocaching friends at parties. It beats card tricks.

 

This happens to me at work all the time. Our mapping system (I'm a GIS manager for an electric/gas utility) uses UTM. When people ask, I always take the time to explain the projection to them along with the concept of datums. It usually results in nodding heads and blank stares, like I'm Capt. Kirk explaining how the warp drive on the Enterprise works. Sometimes people e-mail me with the need to know how to convert map files into our projection. When I tell them to use UTM Zone 16, NAD 27, Clarke 1866 elipsoid, in meters, they usually reply "If you could just do it and send it back....."

 

Thanx! I now know what 12T means. Duh! That is where I am located on this great grid!! 12 is the longitudinal zone and T is the latitudinal zone! It's amazing when you feel like you can make meat out of beans!