[Scilab-users] Surface smoothing in Scilab, immune to outliers

[Dang, Christophe]

Hello, 

De la part de Rafael Guerra
Envoyé : lundi 4 mars 2013 04:37

> Does somebody know if there are Scilab functions
> [...] that smooths
> experimental data z=f(x,y) and is immune to strong outliers.

imho, the problem with smoothing and outliers is that
the definition of a outlier depends on the field.

How can Scilab know what a "strong outlier" is?

I personally would try Fourier filtering:
a strong outlier means a steep slope
and therefore correspond to a high frequency.

Thus fft2, set high frequencies to 0
(with possibly a smooth transition),
then inverse fft2 -- ifft2 does not exist, I never used 2-dimension
Fourier transform so I don't know if the inverse is easy to perform...

-- 
Christophe Dang Ngoc Chan
Mechanical calculation engineer

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