Best Lat/Lon Coordinate System to use?

[+sbur6]

What is the best Lat/Lon system to use?

 

1. DEG/MIN.MM

2. DEG/MIN/MMM

3. DEG/MIN/SEC

4. DEG.DDDDD

 

THANKS

 

Im where?

[Jeremy]

They are all pretty good. The more digits to the right of the decimal point the more precise it is. There was several good posts (like this one) in the past about precision verses accuracy.

 

Jeremy

[MajBach]

what's the difference betweeen #1 and #2. follow with an example, please.

 

MajBach

 

You can't have everything.

where would you put it?

[+Jamie Z]

#2 Should have been written DD°MM.MMM not DD°MM/MMM

 

It's simply one more decimal place precise than #1.

 

Most GPS units display three decimals of minutes. Some (like the Maggie 310) only display two decimal places of precision.

 

So...

 

N35°25.362

W90°15.853

 

is DD°MM.MMM

 

and

 

N35°25.36

W90°15.85

 

is DD°MM.MM

 

The thousandths place of a minute represents about 6 feet of precision, but that does not mean your GPS has 6 feet of accuracy.

 

By the way... I wonder where those coords are?

 

Jamie

[+sbur6]

I dont know what the difference is? Those are the choices available in the 315.

 

Im where?

[+rdw]

The difference is that 2 has an extra decimal place of accuracy. That means you can enter cache coordinates to a greater precision. (Or post them, if you are the hider.) There is no reason to use only 2 decimal precision when you can have 3 decimal places.

 

rdw

[AquaDyne]

quote:

---

Originally posted by sjbur6:

What is the best Lat/Lon system to use?

 

1. DEG/MIN.MM

2. DEG/MIN/MMM

3. DEG/MIN/SEC

4. DEG.DDDDD

---

 

It depends on what you mean by "best".

 

You can display more digits of precision, which might make you think you're more accurate, but in fact the positioning error is bigger than any difference in the displays.

 

I seemed to find caches easier with my first GPSR which only displayed two decimal places for minutes of lat/lon (DEG/MIN.MM) which translates to approximately 50 feet, which is a decent error radius. I knew I was within 50 feet, and searched appropriately.

 

With my newer GPS which displays more precision (DEG/MIN.MMM) I tend to search for the "zero" point but later find out that I'm up to 25-30 feet off from the cache location, especially when there is tree cover.

 

It's your call whether you want to display more digits of precision than you really have accuracy.

[+Maps-R-Us]

The question really isn't which is best, since they all are equally good for the types of GPS receivers most of us use. The default setting is decimal minutes and that is what works on Geocaching.com so that is the best to use. But if you use other software to download coordinates to, then you might want to set your GPSr format to match. An example would be various mapping software only reading one format. MapQuest won't work with decimal minutes so you have to convert. A lot of GIS software only works with decimal degrees since it is easier to do math with a single number and easier to store in a database. I suppose DMS was the only way most people used before we had computers!

[45ºmonkeytree]

Personally, I prefer UTM. Once you understand the system, it is much easier to find locations on a map using one of the plastic overlay grids (I use the one etched into the baseplate of my compass).

 

As a bonus, its easier to estimate distances without having to resort to using the scale since the grids are spaced 1km apart for USGS 7.5' quads.

 

For a good discussion, see this site.

[jfitzpat]

quote:

---

Originally posted by bpacker:

Personally, I prefer UTM. Once you understand the system, it is much easier to find locations on a map using one of the plastic overlay grids (I use the one etched into the baseplate of my compass).

---

I'd have to agree. Being able to estimate distances without having to measure on the map is a real plus. Crossing zones is a pain though.

 

-jjf