Any advantage of the DMS system over the Decimal Degree?

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qquito

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Hello, All:

The Degree-Minute-Second (DMS) system is widely used in geographic coordinates in many places. Google Earth and Wikipedia (in entries of places) are just two ready examples. However, it is pretty much annoying to make notes of the latitude and longitude of a place in the DMS system or to copy/paste them for various purposes. And when you use the latitude and longitude as inputs for some kind of trigonometric computation, you need to convert them to decimal degrees.

So I am wondering if the DMS system has real advantages over the decimal degree in today's world. Who are the people that would prefer the DMS system to the latter?

Thank you for reading!

--Roland
 
qquito said:
So I am wondering if the DMS system has real advantages over the decimal degree in today's world. Who are the people that would prefer the DMS system to the latter?
Click to expand...

Personally, I prefer decimal degrees over DMS simply because there's less cutting and pasting to do. If I have that luxury of course.

For the end user, I really can't see any advantage over any other, other than perhaps if they had one device or software interface that had limited decimal resolution, where the DMS option may offer a higher location resolution. But that's just a software limitation.

Past that point though, there would be little to argue about regarding advantage, mainly because all my devices and applications can cater for pretty much anything.

From a data supplier perspective, one could speculate that database might be smaller, or easier to deal with if they stored locations in one format over another. But even that would be a rather weak argument.

Perhaps it would be more important to state a device, software or other interface *should* offer all the format variations for convenience, rather than for any particular technical advantage.
 
Personally, I prefer decimal degrees over DMS simply because there's less cutting and pasting to do. If I have that luxury of course.

For the end user, I really can't see any advantage over any other, other than perhaps if they had one device or software interface that had limited decimal resolution, where the DMS option may offer a higher location resolution. But that's just a software limitation.

Past that point though, there would be little to argue about regarding advantage, mainly because all my devices and applications can cater for pretty much anything.

From a data supplier perspective, one could speculate that database might be smaller, or easier to deal with if they stored locations in one format over another. But even that would be a rather weak argument.

Perhaps it would be more important to state a device, software or other interface *should* offer all the format variations for convenience, rather than for any particular technical advantage.
Click to expand...

and what about hybrid notation, my Nokia displays lat & long as degrees'minutes'seconds.decimal-seconds ie 52'24'32.45 really it doesn't matter as long as every application you use can be set to the same format.
 
The Degree-Minute-Second (DMS) system is widely used in geographic coordinates in many places. Google Earth and Wikipedia (in entries of places) are just two ready examples. However, it is pretty much annoying to make notes of the latitude and longitude of a place in the DMS system or to copy/paste them for various purposes. And when you use the latitude and longitude as inputs for some kind of trigonometric computation, you need to convert them to decimal degrees.

So I am wondering if the DMS system has real advantages over the decimal degree in today's world. Who are the people that would prefer the DMS system to the latter?
Click to expand...

Older people? Degrees, minutes, and seconds were almost exclusively used 50 or more years ago.

And, no doubt, a mathematician would always prefer degrees with decimal degrees for its purity, clarity, and simplicity.

But to complicate matters, the default today is neither; it is degrees and minutes with decimal minutes. The reason is quite rational---this enables you to determine coordinates from maps more easily.

The reason for this, in turn, is that on a meridian (and along the equator) one minute is one nautical mile, so, for example, to travel 27.5 degrees north, you have to travel 27.5 nautical miles north.

That is why maps, particularly modern, GPS-friendly ones, show minutes, and that is why you are best off, when calling an emergency help vehicle, dictating your position in degrees and minutes with decimal minutes, like this:

"North fourty-eight degrees, three decimal seven eight minutes, east eleven degrees, fourty-one decimal six seven minutes"

(For precision to a few meters you want three decimals, not two.)

Of course, anyone well trained in emergency or search and rescue operations will be able to take coordinates in any of the three common formats. So if you need help very urgently and have your GPS set to the "wrong" format, read it out anyway and ask if it is understood. On the other hand it cannot hurt having your GPS set to the default format of ddd mm.mmm as a precaution.

Hans-Georg
 
Hello, All:

The Degree-Minute-Second (DMS) system is widely used in geographic coordinates in many places. Google Earth and Wikipedia (in entries of places) are just two ready examples. However, it is pretty much annoying to make notes of the latitude and longitude of a place in the DMS system or to copy/paste them for various purposes. And when you use the latitude and longitude as inputs for some kind of trigonometric computation, you need to convert them to decimal degrees.

So I am wondering if the DMS system has real advantages over the decimal degree in today's world. Who are the people that would prefer the DMS system to the latter?

Thank you for reading!

--Roland
Click to expand...

I think the only time DMS would appeal to any real world user would be when trying to transfer coordinates verbally, perhaps over a radio link - only because the extra words involved (the D, M & S) set a sequence that numbers alone won't.

It's tough being confident that an error didn't creep into any verbal handoff of coordinates, and numbers-only seems like the most error-prone to me.

Isn't DMS probably nothing more than a legacy of transits & sextants?
 
......
Isn't DMS probably nothing more than a legacy of transits & sextants?
Click to expand...

I am also curious if it is used today merely because it is a legacy from the past even though it has no perceived advantage but only inconveniences today's users.

---Roland
 
Actually, there is a very real advantage to the use of DD MM SS when working with position/distance

1 minute of longitude at the equator, or latitude, is a distance measurement of 1 NM (nautical mile)

And surely it is obvious that fixing a point to 1/60th of NM is much more precise than fixing point to 1/10th NM

Regards
 
Hello, All:

The Degree-Minute-Second (DMS) system is widely used in geographic
coordinates in many places. Google Earth and Wikipedia (in entries of
places) are just two ready examples. However, it is pretty much
annoying to make notes of the latitude and longitude of a place in the
DMS system or to copy/paste them for various purposes. And when you
use the latitude and longitude as inputs for some kind of
trigonometric computation, you need to convert them to decimal
degrees.

So I am wondering if the DMS system has real advantages over the
decimal degree in today's world. Who are the people that would prefer
the DMS system to the latter?

Thank you for reading!

--Roland
Click to expand...
 
- Show quoted text -
Click to expand...

If you haven't looked at the UTM system you should. It is much more accurate, does not have to be converted, easier to communicate and works with almost everything. It is worth considering it also has a very small learning curve. My opinion, Rick
 
rick said:
If you haven't looked at the UTM system you should. It is much more accurate, does not have to be converted, easier to communicate and works with almost everything. It is worth considering it also has a very small learning curve.
Click to expand...

UTM is useful if you're working with maps, and a standard ruler or length measuring device.

Any ruler distance in any axis on the map, will scale correctly to any real-life distance on the earth's surface. Especially useful when you're dealing with hiking maps.

However, UTM is only suitable for smaller scale maps, otherwise you start to see image "stretching" to fit a spherical surface onto a flat piece of paper. Also, it is not aesthetically "neat" over zones, (degree lines) so the easting and northing lines will appear "tilted" at these borders.

Also, I dispute your claim that it is "more accurate". There is no reason that the UTM projection has particular ability to offer higher accuracy or resolution than any other projection.
 
qquito said:
Hello, All:

The Degree-Minute-Second (DMS) system is widely used in geographic coordinates in many places. Google Earth and Wikipedia (in entries of places) are just two ready examples. However, it is pretty much annoying to make notes of the latitude and longitude of a place in the DMS system or to copy/paste them for various purposes. And when you use the latitude and longitude as inputs for some kind of trigonometric computation, you need to convert them to decimal degrees.

So I am wondering if the DMS system has real advantages over the decimal degree in today's world. Who are the people that would prefer the DMS system to the latter?

Thank you for reading!

--Roland
Click to expand...

# I assume the DMS system you refer to is of the pseudo-decimal notation, similar to BCD (binary coded decimal), whereby numbers are merely placed in sequence, irrespective of actual maths. The full DMS system of degrees, minutes, and seconds, has each being a 60th of the higher value, and decimal equivalent - of minutes and seconds - is merely used for convenience of calculation. It may be possible to convert them all into Base 60, and use that? As with hexadecimal, octal, binary, etc. Then any "decimal" presentation would comply with the rules for column switch, across from right to left. We've become so used to Decimal that Base 10 comes naturally, even if originated from us having ten fingers(toes). Actually, Base 60 would amount to the same as exists at present, except that two columns are used, instead of unity substitutes, as A-F in Hexadecimal. Why then the need of Decimal, if appropriate maths can be applied/devised?
 
DonH said:
# I assume the DMS system you refer to is of the pseudo-decimal notation, similar to BCD (binary coded decimal), whereby numbers are merely placed in sequence, irrespective of actual maths. The full DMS system of degrees, minutes, and seconds, has each being a 60th of the higher value, and decimal equivalent - of minutes and seconds - is merely used for convenience of calculation. It may be possible to convert them all into Base 60, and use that? As with hexadecimal, octal, binary, etc. Then any "decimal" presentation would comply with the rules for column switch, across from right to left. We've become so used to Decimal that Base 10 comes naturally, even if originated from us having ten fingers(toes). Actually, Base 60 would amount to the same as exists at present, except that two columns are used, instead of unity substitutes, as A-F in Hexadecimal. Why then the need of Decimal, if appropriate maths can be applied/devised?
Click to expand...

Because it can be more convenient to use.
 
It may be possible to convert them all into Base 60, and use that? As with hexadecimal, octal, binary, etc. Then any "decimal" presentation would comply with the rules for column switch, across from right to left. We've become so used to Decimal that Base 10 comes naturally, even if originated from us having ten fingers(toes). Actually, Base 60 would amount to the same as exists at present, except that two columns are used, instead of unity substitutes, as A-F in Hexadecimal. Why then the need of Decimal, if appropriate maths can be applied/devised?
Click to expand...

LOL - Actually I just thought of Roman figures. (:-)

Hans-Georg
 
The degrees-minutes-seconds system for angles is, like hours-minutes- seconds of time, a sexagecimal system and has been around (excuse the pun) for a very long time.

It is used extensively, not only in navigation and positioning for geographical coordinates, but also by land surveyors for field angle measurement and for azimuth/bearing display.

While some software may expect decimal degrees, many programs expect DMS values, but in a decimal format. That is, an angle of say 12°13'14" is expected to be input as 12.1314, to make data entry easier (stay on the number keypad). So don't assume that when you see what appears to be decimal degrees input that it is actually decimal degrees in meaning, unless you're sure!

I wouldn't necessarily agree with Peter that 52'24'32.45" represents a hybrid notation; it is just part of the same DMS system, since seconds are not usually subdivided in any other way except decimally. There are, however, slightly more hybrid notations out there, especially in GIS/GPS, that use degrees and decimal minutes (no seconds). Thus 12°13'40" is represented as 12°13.667'

Will we ever likely see the demise of DMS? No. Surveyors are a rather conservative lot ("the oldest profession" and all that) and are very happy with DMS. Even though, as a programmer (of Copan -- a free CoGo program for surveyors) i must say it would be a lot easier to deal with just decimal degrees. Ask yourself, Will we ever see decimal hours instead of the clumsy old hours-minutes-seconds?

Actually, there is a system of decimal degrees in surveying -- it's called gons or grads, but there are 400 of them in a circle! It's popular in parts of Europe.
 
The degrees-minutes-seconds system for angles is, like hours-minutes- seconds of time, a sexagecimal system and has been around (excuse the pun) for a very long time.
......
Click to expand...

Thank you very much! It helps to explain the reason for the persistence of Degree-Minute-Second system. --Roland
 
qquito said:
Thank you very much! It helps to explain the reason for the persistence of Degree-Minute-Second system. --Roland
Click to expand...

Or as my daughters would say in elementary school math class

Curse those Babylonians and their Base 60 numbering system.
 
While some software may expect decimal degrees, many programs expect DMS values, but in a decimal format. That is, an angle of say 12°13'14" is expected to be input as 12.1314, to make data entry easier (stay on the number keypad). So don't assume that when you see what appears to be decimal degrees input that it is actually decimal degrees in meaning, unless you're sure!
Click to expand...

That's hair-raising!

Hans-Georg
 
That's hair-raising!
Click to expand...

I found out the hard way that web databases can be similarly wrong e.g. in Scotland, Edinburgh Airport is here:- 55°57'0" N, 3°22'21" W
55.95, -3.3725
Elevation 33 feet
ICAO code EGPH

One (of many) web sites that attempt to provide weather information by location is:- <http://www.metcheck.com/V40/UK/FREE/tomorrow.asp?zipcode=egph> gives this information which you will note has expressed the known LAT and LON in degrees:-
Lat : 55.6N Lon : 3.2W ASL : 605m

and the weather is of course slightly different that further South and up a hill!

Specifying the location by post code gives the correct information <http://www.metcheck.com/V40/UK/FREE/today.asp?zipcode=eh129dn > EH12 9DN
Lat : 55.9N Lon : 3.3W ASL : 11m

The web site owner simply shrugs it off as that was the data in the database they purchased...
 
Which part of the airport is at that position ???

A major airport would likely span at least 0.3 degrees, especially sited at a latitude near 60 degrees. AT that latitude, a distance on ground of 2 miles would equate to around 2.6 degrees longitude
 

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