| Re: Calculating area of latitude-longitude quadrangle? [message #77311] |
Wed, 24 August 2011 00:54 |
Maxwell Peck
Messages: 61
Registered: February 2010
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Member |
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On Aug 24, 4:52 am, Ashley Berg <ashley.b...@gmail.com> wrote:
> Is there any way to calculate the area of a latitude-longitude
> quadrangle in IDL, or some formula I could use?
> MATLAB can (using areaquad from the Mapping Toolbox, which can return
> surface area in km^2 of a lat/lon box covering a part of Earth) but I
> do not have access to MATLAB.
When I had to do something similar in Excel (don't ask!) I broke it up
into two triangles, found the internal angles (google Aviation
Formulas) and used Girard's theorem to find the area of each triangle
and added them together.
Max
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| Re: Calculating area of latitude-longitude quadrangle? [message #77322 is a reply to message #77311] |
Tue, 23 August 2011 13:37  |
R.G.Stockwell
Messages: 163
Registered: October 2004
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Senior Member |
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>
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> "Ashley Berg" wrote in message
> news:7e751dd7-f940-4246-bb73-a68fad00140d@bl1g2000vbb.google groups.com...
>
> Is there any way to calculate the area of a latitude-longitude
> quadrangle in IDL, or some formula I could use?
> MATLAB can (using areaquad from the Mapping Toolbox, which can return
> surface area in km^2 of a lat/lon box covering a part of Earth) but I
> do not have access to MATLAB.
actual surface area would be impossible, but just integrate the surface of a
sphere and that could get you close enough.
cheers,
bob
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| Re: Calculating area of latitude-longitude quadrangle? [message #77325 is a reply to message #77323] |
Tue, 23 August 2011 12:13 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Ashley Berg writes:
> Is there any way to calculate the area of a latitude-longitude
> quadrangle in IDL, or some formula I could use?
> MATLAB can (using areaquad from the Mapping Toolbox, which can return
> surface area in km^2 of a lat/lon box covering a part of Earth) but I
> do not have access to MATLAB.
Wow! Really!?
I'm not sure I'd put a whole lot of trust in a
number like that! :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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