Horizon display problem

[Magnus Lidgren]

Hi all

I have run into a strange horizon display problem.
 
The workflow for my 3d seismic cube I use goes like this:
1. I create my own attribute. The attribute include setting limits, excluding a minor population of “out of range values”, i.e. using the math formula:
x1<0.96 || x1>1.04 ? undef:x1

2. I run “create seismic output” and get an output cube with values between 0.96-1.04
together with a minor amount of values set to undefined, i.e set to 1e30

3. I load a horizon of interest and display the attribute result cube on the horizon.
The display problem comes with the result “extreme” values displayed on the horizon, seems that values close to undefined values 1e30 are interpolated to “extreme” values close to either plus 1.e30 or minus 1-e30.

A histogram of the displayed horizon looks like below.

 

The attribute correct histogram from an inline looks like this.
 


Below an example of the Display problem values on a horizon. Nearby Green values are undefined values.

So, I end up with a picture partially populated with incorrect extreme high/low values.

A hypothesis is that the shown "extreme values" always have "undefined 1e30" neighbours.

I would be grateful for any work around suggestions.
(or perhaps this might be something to address for upcoming program updates)

Best regards
Magnus Lidgren
Lund, Sweden

[Paul de Groot]

Hi Magnus,

I've tested your attribute but cannot reproduce your result. The only thing I can suggest is to have a look at the squeeze option of the scaling attribute. With this option you can squeeze outliers to a user defined range.

Best regards,

Paul.

--

Paul de Groot

Geoscience Manager

-----------------------------------------------------------------------------------------------------------------------   dGB Earth Sciences
Phone: +31 53 4315155 E-mail: paul.d...@dgbes.com Internet: dgbes.com

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[Magnus Lidgren]

Hi Paul,

Thanks for your reply to my display problem.

I have played around with the F3Demo cube to see if I can reproduce the strange result using that seismic.
And yes, the same thing happens when I exactly followed the workflow I used previously with my own cube

The "illness" seems to be related to preloading the attribute result cube.

If I use preloaded data the problem shows up.

If the cube is not preloaded all works fine. See below

Preloaded result                                                Not preloaded

So I guess that I have found a work around. 

It would of course be nice to be able to use preloaded data, since the results show up much faster.

Best regards

Magnus

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[Paul de Groot]

Hi Magnus,

This is a bug. I have been able to reproduce it and will report it. To save time, you could save your attribute as "horizon data". Restoring horizon data is faster than retrieving from file and much faster than recomputing the attribute.

Best regards,

Paul.

--

Paul de Groot

Geoscience Manager

-----------------------------------------------------------------------------------------------------------------------   dGB Earth Sciences
Phone: +31 53 4315155 E-mail: paul.d...@dgbes.com Internet: dgbes.com

----------------------------------------------------------------------------------------------------------------------- 

To view this discussion on the web visit https://groups.google.com/a/opendtect.org/d/msgid/users/CADRo4ws9qYnEs4h43PCHwObG%2B%2BjCL6tWtPRLTrAE86h2vBQLXg%40mail.gmail.com.