I am calibrating my landsat data to reflectance with correction for sun angle. I just want to know if sun angle is computed as such θsin(sun_elev), where sun_elev is the sun elevation value specified in the landsat 8 metadata.
Answer
Calibrating Landsat-8 OLI to Top of Atmosphere:
R_toa_Bx = (M_Bx * DN_Bx + A_Bx) / sin (Sun_elev)
Where R_toa_Bx is reflectance in band_x, M_Bx is the multiplication factor stated in the metadata file, DN_Bx is the digital number in band_x from the TIFF-file, A_Bx is the addition number stated in the metadata file and Sun_elev is the sun elevation angle stated in the metadata file.
The most common mistake is problems with degrees and radians. As such, if your numbers are totally wrong, try changing sin (Sun_elev) to sin (Sun_elev * Pi / 180).
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