Hi Bob,
Check out
http://www.anzlic.org.au/icsm/gdatm/chapter4.htm
The Vincenty's formulas are one of the the best ones around. And I quoate
the above page:
Vincenty. s formulae (Vincenty, 1975) may be used for lines
ranging from a few cm to nearly 20,000 km, with millimetre
accuracy.
There is also an Excel spread sheet there. Programming the formulas will
take a lot of care, have fun. Someone else here coded the inverse formulas
and I was asked to program the direct formulas. They are complex formulas
but at least if you just want to use them, you don't have to understand
them. Just be careful with the inverse tan functions. If you have any
problems at all, do email me and I will try my best to help you.
Cheers,
Nancy
------------------------------------------------------
Nancy Jarrott Email: [EMAIL PROTECTED]
Software Engineer Tel: 61 7 3004 6706
Agsystems Pty Ltd Web: www.agsystems.com.au
------------------------------------------------------
"Bob Young -
www.bydesignwales.dem To: [EMAIL PROTECTED]
on.co.uk" cc:
<[EMAIL PROTECTED] Subject: MI Accurate distances
around the world
mon.co.uk>
Sent by:
owner-mapinfo-l@lists
.csn.net
11/05/2000 21:23
Dear List
This is a general GIS question rather than MI specific.
Does anybody know where I can find a formula for measuring the distance
from one long, lat to another long, lat anywhere in the world?
I am not worried about the complexity of the formula. I am more
concerned about the accuracy of the answers obtainable from the formula.
ALSO:-
Does anybody have any experiences ( good or bad ) on the accuracy of the
answers from MapInfo Professional on distance measurement? Does anybody
know the method employed within MI Pro?
Thanks,
Bob Young
www.mapsbydesign.co.uk
--
Bob Young - www.bydesignwales.demon.co.uk
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