Which Readout Is Best

[earthshaker]

Everyone involved in geocaching must have a preferred position readout, Which is most accurate? deg,min, sec ddmm.xx, utm, dd.xxx, or another system I didn't list(I don't have my gpsr handy)

[+Hemlock]

Since the site uses DD MM.MMM, all other formats are superfluous for geocaching. This format provides accuracy to about 6 feet, which is far better than consumer grade GPS receivers.

[uperdooper]

Since the site uses DD MM.MMM, all other formats are superfluous for geocaching. This format provides accuracy to about 6 feet, which is far better than consumer grade GPS receivers.

what he said.

[Bobthearch]

I prefer UTM, because UTM numbers are actual measurements (meters) and because fractions suck.

 

How far is a thousandth of a minute anyway, and who wants the hassle of trying to figure it out?

 

Scientists generally use UTM coodinates, and the use of the UTM system is mandated by many goverment agencies.

 

-Bob

[+woody_k]

I prefer UTM, because UTM numbers are actual measurements (meters) and because fractions suck.

 

How far is a thousandth of a minute anyway, and who wants the hassle of trying to figure it out?

 

Scientists generally use UTM coodinates, and the use of the UTM system is mandated by many goverment agencies.

 

-Bob

I have a friend who uses UTM. So this opinion is only based upon what I see he does with it.

 

UTM, like you said, measurements and can tell you how far it is to get GZ...but WGS84 tells you in a more precise way exactly where you are.

 

I am sure there is more to it but when caching with him I seem to do better at locating where the cache is than he.

 

Ken

[+Renegade Knight]

WGS 84 as used by this site (DDD MM.MMM) is accurate to 6' give or take as has been said. UTM is accurate to 1m as used by this site.

 

Your GPS is accurate to 10-20' depending on signal quality and other variable. Coordinates are already more accuate than the GPS accuacy. For the moment more accurate coordinates are a moot point.

 

Some people who borrow their work GPS use NAD 27 since that matches topo maps and they want to keep consistant with work.

 

However for the most part you use WGS84 because then you don't have to translate anything and that lessens the chance for a mistake. If you need to do math with coordinates then you can't beat UTM because the numbers are real and they mean something. Latitude and Longigute in WGS 84 are a coordinate system in an ellipsoid. The math can be complex.

[+Marky]

UTM measurements are only really valuable if you are doing paper navigation or mathimatical distance calculations. If you are using a GPS, it tells you all the distances for you, so it doesn't really matter which coordinate system you are using. Much easier to just go with the flow and use the coordinate system that GC.com uses. Of course, if some other coordinate system turns you on, then by all means feel free to use it.

 

--Marky

Edited December 2, 2004 by Marky

[CoyoteRed]

WGS84 and DD° MM.MMM is the standard and what most people use. The most accurate would be using the same format as the hider and considering the hider more than likely used WGS84 and DD° MM.MMM...

[+tirediron]

Gotta go with CR on this one!

[Bobthearch]

I guess now I gotta ask, why does geocaching.com use a non-standard system? Nearly all usgs topo maps are still NAD27. What makes WGS84 better than NAD27 or NAD83?

 

Becoming very curious,

-Bob

[+SixDogTeam]

all other formats are superfluous for geocaching.

Uh, not really. Each cache page also lists UTM, which we use exclusively and it's not superfluous. You can use any system you want as long as you can translate it at a site, such as JEEEP.

[Bobthearch]

hmmm... with two minutes of research and a small experiment, it seems NAD83 and WGS84 are the exact same. Can anyone elaborate or correct me if I'm wrong?

 

In my location, NAD27 and NAD83/WGS84 are ~way~ different.

-Bob

[CoyoteRed]

I guess now I gotta ask, why does geocaching.com use a non-standard system? Nearly all usgs topo maps are still NAD27. What makes WGS84 better than NAD27 or NAD83?

Apparently, for some reason, consumer grade GPS units come that way from the factory. Saves one step getting newbies out caching.

[+Renegade Knight]

hmmm... with two minutes of research and a small experiment, it seems NAD83 and WGS84 are the exact same. Can anyone elaborate or correct me if I'm wrong?

 

In my location, NAD27 and NAD83/WGS84 are ~way~ different.

-Bob

For all intents and purposes they are.

[+Markwell]

I guess now I gotta ask, why does geocaching.com use a non-standard system?  Nearly all usgs topo maps are still NAD27.  What makes WGS84 better than NAD27 or NAD83?

 

Becoming very curious,

-Bob

NAD83 and WGS84 are essentially the same in North America (North America Datum 1983, and World Geodetic System 1984). I've heard tell that the system is not as similar on other continents.

 

NAD27 (North America (North America Datum 1927) might be more standard on Topo Maps, but it is not the most up-to-date datum, and NAD83 corrected a lot of problems.

 

Not that I know anything about what the problems were with NAD27

[Bobthearch]

Thanks for the info. I know many government agencies allow either NAD27 or NAD83. On the gov't forms you usually check the box according to which you're using, which is generally determined by the particular topo map you're working with.

 

I don't know anyone who uses anything other than UTM for government or scientific work. Geocaching is just odd that way I guess...

 

-Bob

[+Markwell]

Also remember that UTM is based on a flat earth Mercator Projection, which distorts the farther toward the poles.

 

So, if the world were indeed flat, yes - UTM would be perfect.

[+The Puzzler]

I don't know anyone who uses anything other than UTM for government or scientific work.  Geocaching is just odd that way I guess...

Three comments:

 

1) My understanding is that the big differrence between NAD27 and WGS84 it that the fundamental model of the shape of the earth is different. WGS84 (and I assume NAD83) are based on models of the earth surface that are much more accurate than the simpler older models that older systems were based on. As such, for any given place the difference between NAD27 and WGS84 can be from nothing to several 10s of meters (worst cases I think is over 100 m).

 

2) I am an oceanographer, and given the few years of my life I have spend navigating the sea and studying it as a scientist, and based on the few 1000s of pages of technical literature that I regularly read, I have never noticed any ocean oriented scientific lieturature that gives locations in UTM. They are all degrees, minutes, seconds or degrees minutes. Of course, for everything except the the recovery of moored instruments, we don't generally care where we are to better than many hundreds of meters.

 

3) As for converting latitude and longitude into distance, unless you are traveling directly north, south, east, or west you have to do some calculations regardless of whether you use UTM or DDD MM.MMM, and how hard is it to think of 0.001' latitude as 6 ft and 0.001' longitude as 4 ft.

 

0.001' of latitude is always and everywhere essentially 6 ft.

0.001' of longitude is just the cosine of your latitude times 6 ft or

 

x=cos(latitude)*6 ft on your calculator.

 

After figuring out your longitude distancce conversion just once, unless you travel a fairly great distance north or south, you never have to determine it again.

[Bobthearch]

2) I am an oceanographer, and given the few years of my life I have spend navigating the sea and studying it as a scientist, and based on the few 1000s of pages of technical literature that I regularly read, I have never noticed any ocean oriented scientific lieturature that gives locations in UTM. They are all degrees, minutes, seconds or degrees minutes. Of course, for everything except the the recovery of moored instruments, we don't generally care where we are to better than many hundreds of meters.

 

There 'ya go. I was wrong. I wonder if it's because of ocean navigation tradition? They don't use USGS topo maps in the Atlantic Ocean either. Most of my gov't interaction has been recording archaeological sites for various state and federal agencies - BLM, Forest Service, state archaeological services, highway departments, etc. They all use UTM.

 

I took an oceanography class in college. Way cool! But I went into archaeology instead, and now geology. I am curious to find out if tolerance for sea-faring is genetic, or if I'd get as sick as a dog.

 

-Bob

[+The Puzzler]

I am curious to find out if tolerance for sea-faring is genetic, or if I'd get as sick as a dog.

I don't doubt that you hit on the two central issues: tradition and the use of USGS maps (although, I've seen these with degrees and minutes on them before) instead of navigational charts.

 

Also, since meter by meter measurements are key in archeology, a square grid would be very handy. In the ocean, probably having a more global system instead of having to switch grids from place to place is an advantage. Heck, when we get off shore far enough, we don't even plot our courses on charts, we just use large blank sheets of paper - cheeper and just as effective.

 

With degrees and minutes, you can calculate distances from any spot on the earth to any other in a very consistent way. With UTM, you would have to do all kinds of grid translations (I would think anyway) and then convert those darn metric units into knotical miles so that captain could understand you.

 

In the end, for geocaching, I don't think it probably makes much difference one way or the other.

 

As for sea-faring tolerance, I've only met one person that has spent extensive time at sea and not been seasick on occation. I've met many that struggled for a long time with horrible sea sickness, only to eventually become very sturdy sea dogs. Genes may play a role, but experience is by far the most important for this one. Physical fitness also makes a big difference.

[+AtoZ]

My dad in 13 years of commerical fishing NEVER got seasick once, UGH!!!

Ol well for Grocaching UTM is best., as most caches are within a very short distance but if you flying from LA to London then maybe Lat/Long would be best. A good mechanic uses the correct tool for the job. Don't drive tacks with a 5# sledge hammer. SO for geocaching UTM is good because you can relate better to 10 meters north and 20 meters east of where you are then 0.054 minutes. Just my thoughts

cheers

[CoyoteRed]

Ol well for Grocaching UTM is best., as most caches are within a very short distance but if you flying from LA to London then maybe Lat/Long would be best.  A good mechanic uses the correct tool for the job.  Don't drive tacks with a 5# sledge hammer.  SO for geocaching UTM is good because you can relate better to 10 meters north and 20 meters east of where you are then 0.054 minutes.  Just my thoughts

cheers

I suppose, if you're inclined to think in coordinates and whatever offset is in coordinates.

 

Me, after the unit is loaded I don't mess with coordinates much. I select a waypoint and the unit tells me "X distance, that way." I like it like that.

[Bobthearch]

I select a waypoint and the unit tells me "X distance, that way." I like it like that.

 

GPS units do that no matter which measurement system or which datum you're using. But I see your point. Most people probably leave their unit the way it came from the store.

 

Best Wishes,

Bob

[Jeremy]

I guess now I gotta ask, why does geocaching.com use a non-standard system? Nearly all usgs topo maps are still NAD27. What makes WGS84 better than NAD27 or NAD83?

Because we like it when we have less emails in our contact@geocaching.com in box.