[Users] Question : Importing Steering Data

[Arnaud Huck]

Dear Colin,
If you want to minimize your storage space and to go quick, the most convenient way to use your previous steering cube is to create a link,
into OpendTect,from your under-sampled survey to your full resolution steering cube. Please note that, even if you can, there is no need to 
decimate your full resolution steering into a new steering cube volume.

If your survey has a step of 50m x 50m, you can still use volumes with spacing 12.5m x 12.5m, or 25m x 25m, or any possible (sub-) multiples. 
OpendTect will take care of the decimation every time that you would like to display or process your data.

So, the fastest way to link your steering cube is to go via File --> Import --> Seismics --> CBVS, since the steering cube are in the same 
format as any other seismic / attribute volumes. The only difference is that they contain two compenents (respectively inline and crossline dip).

1) Browse in order to reach your previous steering cube.
2) "Cube type" is "Steering cube".
3) Import mode can be "Copy the data" (creates a new volume in the current survey), or Use-in-place, which will set a link. The choice for 
this option will depend on your network configuration (working remotely or locally). With the option "Copy the data", you can manually decimate 
your data as the survey is with sampling 50m x 50m. Then change the step in the "Volume selection" area from 1 to 4.
4) Give a name in this survey for this new steering cube, or for the link.

In the user documentation, when we say that "Dip values should be non-negative and should be in usec/m, or in m/m if your survey is in 
depth rather than time.", we refer to polar dip values, which are defined as the squarre root of the sum the squarre inline dip and 
squarre crossline dip. Therefore, polar dip is always positive.

Let me add a comment about the "Steering Import” functionnality. The option is only meant to enable you loading steering data from a 
non-OpendTect software. Indeed, two component volumes are not very common, so other packages might split them into a volume containing 
polar dip information, and a second volume containing azimuth dip values. In case you want to merge such volume into an OpendTect steering 
cube volume, you will need to use this option. As long as you go from OpendTect to OpendTect, it will be much more convenient for you to load 
your file under File --> Import --> Seismics --> CBVS.

Best regards,
Arnaud.

-- 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



Colin Hawke wrote:

> I have a simple question but it is proving to be a little hard to 
> resolve. I have calculated and filtered a steering cube on a 10 
> million trace / 6.5 sec record 3D dataset with a 12.5m x 12.5m bin 
> spacing. I have created another project that I have sub-sampled this 
> to a 50m x 50m bin spacing and now I want to use the steering cube I 
> have previously calculated in the full resolution project. How do I do 
> this easily? I thought of calculating the inline and crossline dip 
> from the full resolution survey and then importing it with “Steering 
> Import” but this wouldn’t work as the inline & crossline dips contains 
> both positive and negative values which according to the documentation 
> aren’t allowed. I am sure I can think of some work around but because 
> of the size of the datasets involved I don't want to waste any more 
> time than is necessary.
>
> Regards, Colin
>
>
>
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> Users at opendtect.org
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>


-- 
-- 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