[Users] How-to: extract a 3D enveloppe of a chimney ?

[Friso Brouwer]

Dear Aurelien,

For 2D displays: What we do often is display multiple attributes 
(layers) on one inline. On the base layer you can display a full stack 
or similar seismic display so you will have a context. On the higher 
layers you can display attributes such as your chimney. The trick is for 
the higher layers to make part of the colorbar transparent and/or make 
the layer as a whole transparent, such that you can appreciate the 
context (seismic) and attribute in one view. For convenience OpendTect 
has a default colorbar called chimney of which the lower part is 
transparent. Below some links to the manual entries that will enable you 
to do this.
Manipulate lines (to add more layers): 
http://www2.opendtect.org/rel/html/x131.htm#AEN374
Manipulate colorbar: 
http://www2.opendtect.org/rel/html/x131.htm#LINK-COLOR.EDIT

For  interpretation of the chimney you can use multiple sections/slice 
in different directions which will give you a good feeling about the 3D 
character and morphology of the chimney.

For 3D displays: Load the data in a volume display element. Then use the 
volume rendering option. The trick is to use a colorbar which is 100% 
transparent for most of the range and only shows the upper ~5% of the 
actual data range. This because in volume view the (partial) transparent 
works similar to a fog, one can only see so deep in the object and 
setting the cut-off to low would obliterate the view on the core of the 
chimneys - often to get this exactly right you need to play around a 
little bit with the color bar cut-offs. Below the link to the manual 
entry regarding volume rendering:
http://www2.opendtect.org/rel/html/x131.htm#AEN444

I hope to this solves you question. If there is anything unclear shoot 
me an email anytime.

Cheers,

-- 
Friso GC Brouwer
Chief Geophysicist

dGB-USA
One Sugar Creek Center Boulevard
Suite 935
Sugar Land, TX, 77478

Tel 281 240-3939 (main)
Tel 281 240-6957 (direct)
Fax 281 240-3944
e-mail friso.brouwer at dgb-group.com
http://www.dgb-group.com



Aurélien wrote:
> Dear OD users,
>
> I did a Chimney cube using the standard procedure. So, it means that I 
> have a very nice chimney :-)
> But now, I would like to represent it in 3D as it looks like a very 
> nice plume through sediments (see picture attached)
>
> There is several issues to do this:
> 1) propagate something between the chimney and the non-chimney (user 
> controlled) to get the enveloppe in 3D.
> 2) remove all the data and/or values with a "chimney amplitude" lower 
> than x (x= limit between chimney and non-chimney) and display the result.
> 3) I don't know yet ;-)
>
> I didn't find any tool able to perform it in OD.
>
> Does anyboby knows how to ?
>
> Hope I am clear.
>
> Cheers,
>
> Aurelien Gay
>  .     .
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