I think a good place to get information is the book by Jean Meeus. The
requisite equations for the sun's azimuth and elevation are given in his
Ch. 13 as eqns. 13.5 and 13.6. His chapters 25 (Solar Coordinates) and
26 (Rectangular Coordinates of the Sun) might also interest you.
Don Snyder
On 8/23/2011 9:29 PM, Donald Christensen wrote:
I need to write a spreadsheet to find the sun position. I know there
are already many programs that do this. However, I need to write one
myself because:
1. I'll learn as I write
2. It will give the sun position in the format that I need
3. I can tweak the spreadsheet to give the same answer but in another
format.
My question is, where do I start?
I want to input
Latitude
Longitude
Time
The sun position will then be in X Y Z coordinates.
I'll back up. I'm drawing a sundial in Autodesk Inventor. I can place
lights that represent the sun. I can move the lights while I film my
animation and watch the shadows move.
That's why I need the sun position in XYZ format. I want the shadows
accurate. I don't need the sun to be 150,000,000 km away from my
sundial. It only needs to be 100 meters away
I want to first write it to output azmith and altitude. (or the same
as other programs whatever the output is) I'll then tweak my
spreadsheet to convert this to XYZ
--
Cheers
Donald
0423 102 090
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So there!
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