[Users] Phase rotation?

[Arnaud Huck]

Dear Users,
It is not possible to apply any phase rotation in OpendTect. 
Nevertheless, it is possible to apply a -90, +90 or 180 degrees phase 
rotation to your data.

A 180 degrees phase rotation is trivial. It corresponds to a complete 
change of sign. A attribute of type mathematics, with formula c0*x0 
(c0=-1, x0=input data) will do the job.

A -90 degrees phase rotation is even more easily accessible, through the 
Hilbert transform. Indeed, the Hilbert transform rotates the negative 
part of the frequency spectrum by +90 degrees, and it rotates the 
positive part of the frequency spectrum by -90 degrees. As the seismic 
data is real and not complex, applying the Hilbert transform will then 
rotate your signal by -90 degrees.
The Hilbert transform is available as an attribute of type 
"Instantaneous", with the option "Hilbert".

A +90 degrees phase rotation becomes accessible when combining the 
previous two preceding operations, using two attributes. That is 
applying a Hilbert transform (rotation of -90 degrees), and taking the 
opposite sign (rotation of 180 degrees).

Best regards,
Arnaud Huck.

-- dGB Earth Sciences B.V.
-- Nijverheidstraat 11-2, 7511 JM Enschede, The Netherlands
-- mailto: arnaud.huck at dgb-group.com, http://www.dgb-group.com
-- Tel: +31 53 4315155 , Fax: +31 53 4315104



Simon Crombie wrote:
> Can I use opendtect to apply a constant phase rotation to a seismic volume?
>
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