2D SEG-Y Elevation Issue

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TimPoole
TimPoole Posts: 3
edited July 2021 in Leapfrog
Using the new Geophysics module in Leapfrog Geo I've been trying to import some 2D SEG-Y files that I have downloaded from SARIG (line 86AK-7)

The profiles plot in the correct XY location however they plot well below the topographic surface.

I've played around with different import parameters but the best I can get is about 300m below the actual topographic surface. 



One thing I have noticed is that Leapfrog brings in or calculates the elevation at -(minus), the screen grab below shows the XYZ for a location on the profile. The elevation is -155m. The actual elevation is 155m which is why its plotting ~300m below the surface. 



Does anyone have any experience or can help in bringing these profiles into Leapfrog Geo at the correct elevation?

Thanks
Tim
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  • jasonMcIntosh
    jasonMcIntosh Posts: 7 Staff
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    Hi Tim 

    Currently when you import a SEG-Y file, the default "first sample at" is correct for Time but wrong for Depth. The user should change this to the channel at byte loc 53 or 57 (source/receiver elevation datum). This should place the section at the correct location on the Z-scale. 

    We will look at fixing the incorrect default for a future release.

    Thanks,
    Jason
  • TimPoole
    TimPoole Posts: 3
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    Hi Jason

    I have tried that, I've also tried using byte location '41 receiver group elevation' and '45 surface elevation at source' but it still plots about 150m below topo.

    However using a 'double bluff' type method and setting the First sample at "User" then -150 this does set the top profile elevation to 150m.



    This will work for what I need here as its fairly flat but its not ideal.

    Thanks
    Tim

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