Rayleigh correction by Py6S

[Liang Danping]

Hello everyone, 

I want to get rayleigh correction reflectance by Py6S, and I find this page (Calculating Rayleigh Reflectance using Py6S « Robin's Blog (rtwilson.com)). 

I am a newer in Py6S, so I just replace some parameters in this code which is used to get BOA of Sentinel-2 (AtmosphericCorrection/AtmosphericCorrection_Sentinel.py at master · Zhaoguanhua/AtmosphericCorrection · GitHub).

In the origin code, it applys xa, xb, xc to the whole image to complete atmospheric correction. If I ignore this statement or parameter, it cannot gives a result. If I did not delete this statement, it works. 

s.atmos_corr = AtmosCorr.AtmosCorrLambertianFromReflectance(-0.1)

And I cannot find relevant parameter in the blog. So I want to ask that in the rayleigh correction, how to edit this statement to get xa, xb, xc?

Looking forward to your reply! 

Yours,

Diane