topic Re: Degrees Minutes Seconds - Decimal Degrees changes the Degrees integer in Coordinate Reference Systems Questions

Degrees Minutes Seconds - Decimal Degrees changes the Degrees integer

deleted-user-yUw6wWKCYBY0 — Tue, 18 Oct 2016 12:07:08 GMT

I have been given a spreadsheet containing Degrees Minutes Seconds coordinates in the format 'DD MM SSS' (including the spaces). I've used the DMS - DD formula ‘DD = (Seconds/3600) + (Minutes/60) + Degrees' to convert the DMS values to DD. I have also used the Convert Coordinate Notation tool in ArcMap. Both methods agree that my DMS of 53° 47’ 985” = 54.05694. This would seem to be because the seconds contain three digits when they should contain only two. Does anyone have any ideas as to how this could have arisen? I'm now thinking that what I have is in fact Degrees, Minutes, Decimal Seconds.

Re: Degrees Minutes Seconds - Decimal Degrees changes the Degrees integer

DanPatterson_Retired — Tue, 18 Oct 2016 17:52:54 GMT

well more than that is wrong since there is no way of getting 54 degrees in any event.

consider 54 deg 54 min 54 seconds

54 deg 54 +54/60 min

54 deg 54.90 min

54 deg 54.9/60

notice it never gets to 55, no matter how hard you try.

quit trying to use those old formula since they lead to errors, just use sequential math and you will notice that you don't 'add' to the degree portion it 'becomes' the decimal portion a conceptual versus mathematical difference

Re: Degrees Minutes Seconds - Decimal Degrees changes the Degrees integer

JayantaPoddar — Tue, 18 Oct 2016 19:00:24 GMT

You guessed it right. The value of Seconds should be less than 60. The calculation seems correct but the Seconds' value seems incorrect.

It may seem correct if I consider it as Degree Minute (decimal), not DMS. e.g. 53° 47’ 985” looks incorrect, but it could be 53° 47.985'.

Please check with the data provider.

Re: Degrees Minutes Seconds - Decimal Degrees changes the Degrees integer

deleted-user-yUw6wWKCYBY0 — Wed, 19 Oct 2016 12:11:36 GMT

Thanks Dan, yes of course the DMS integer of 53 degrees can never become a DD integer of 54 degrees which means that my example calculation produces an incorrect result. I believe that the calculation is sound in principle however this is a textbook case of rubbish in - rubbish out! Thanks for your feedback.