Zenith-Azimuth Angle Calculation for off nadir Instrument

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Last Post 25 Mar 2012 02:25 AM by anon

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anon

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25 Mar 2012 02:25 AM
Hi, I need to calculate Zenith and Azimuth Angles for FLAASH input, from following information available: Sun Azimuth 139.908233 Sun Elevation 41.539439 Satellite Inclination 98.19 Look Angle -2.2875 This is Hyperion data of year 2010..Does anyone know how to get the correct values. Thanks -Anuj

MariM

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26 Mar 2012 07:35 AM
This forum thread discussed the Hyperion zenith and azimuth angles which should be helpful: http://www.exelisvis.com/...612/scope/posts.aspx

Deleted User

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27 Mar 2012 12:10 AM
Thank you MariM, I have already gone through the post, however, it has not cleared my doubt. I believe FLAASH require satellite Zenith & Azimuth angles, which need to be calculated using information given in metadata file like Satellite inclination, look angle and sun azimuth etc... That post suggest that "The look angle should be equivalent to the satellite's zenith angle" but ENVI help manual suggest that "Zenith angles must be positive and between 90 and 180 degrees".

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27 Mar 2012 04:15 AM
Your satellite zenith angle is 180 degrees - the absolute look angle. So: 180 - 2.2875 Azimuth is slightly harder to get, and can't be determined directly from the metadata. But your almost at nadir, you might just want to correct it as nadir.

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