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20040120: McIDAS calculation of satellite view angles



>From: Melanie Wetzel <address@hidden>
>Organization: University of Nevada-Reno/DRI
>Keywords: 200401202253.i0KMrAp2021098 McIDAS PLAX

Hi Melanie,

>Hello!  Is there a McIDAS utility or program that can calculate the
>satellite viewing angles and sun angles to pixels of an AREA satellite
>image, and export these (such as AXFORM exports Lat/Long parameters) ?

Not in the way I think you want.  There is a routine called PLAX
that calculates the parallax at the cursor position (it is an
interactive routine), however.  The calculations that PLAX makes
is probably close to what you are looking for.  The source code
for PLAX is found in ~mcidas/mcidas2003/src/plax.pgm.

This desire has been discussed in the past by others.  I will have
to sift through the inquiry tracking system for info that was
given previously, but I won't be able to do it until at least
tomorrow.

>I would like to use that information with radiative transfer model
>results.

Do you need the angles at every point?

Tom

>From address@hidden Thu Jan 22 09:00:25 2004

>Hi Tom,

>Thanks for your reply.  I will look for plax.pgm, but I don't expect it
>will have all the code needed, since I think the parallax corrections
>account just for satellite-earth geometry and not also
>sun-earth-satellite angles.

>Yes, I would need the angles between pixel and sun, and pixel and
>satellite, at every pixel.  I do this with TeraScan software now, and
>was hoping to do the same with McIDAS software.  The parameters are
>used with lookup tables and interpolation methods that compare the
>results of radiative transfer (scattering) calculations for clouds for
>varying sun and satellite view angles, to match theoretical cloud
>radiative properties to observed cloud reflectance, near-infrared
>radiance and thermal radiance.  I expect someone, somewhere has created
>a program for McIDAS to do this, for example to correct the 3.9-micron
>channel to remove the reflected solar radiance component, but I do not
>know who that might be.

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