[GRASS-user] [GRASS-dev] Does SUN_ELEVATION in Landsat's MTL file mean zenith for i.topo.corr?

[Yann Chemin]

Hi Nikos,

generally zenith angle = 90 - SUN_ELEVATION ANGLE indeed.

Cheers,
Yann

On 8 January 2013 21:08, Nikos Alexandris <nik at nikosalexandris.net> wrote:
> Sorry for cross-posting.
>
> I would like a confirmation for the following, regarding i.topo.corr:
>
> Is SUN_ELEVATION the requested zenith parameter (by i.topo.corr)?
>
> So, given the entry "SUN_ELEVATION = 45.38304417" in the the metadata file
> "LT51840322011266MOR00_MTL.txt", then, the production of an illumination model
> requires "zenith=45.38304417".
>
> Or is it "zenith = 90 - SUN_ELEVATION", thus it becomes
> zenith = 90 - 45.38304417 = 44.616956
>
> ?
>
> Thank you, Nikos
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-- 
Yann Chemin
Researcher at IWMI
Skype/FB: yann.chemin