[Users] Loading SEG-Y files with decimal degrees

[Gery Herbozo Jimenez]

Hi Bert and Arnaud,
 
Thanks for your reply and sorry for my late answer. Well, what can I say, what you explain it's what happens and an important issue indeed (build the perfect SEG-Y reader package) because there are some software that produce SEG-Y files with decimal degrees as coordinate values. Actually, since some time ago I work with subbottom profiles and now with boomer data. The software used to obtain the field data it is the sonarwiz.map (probably you have heard about it), and it gives two choices as output: (1) decimal degrees scaled by -10 000, and (2) arcseconds. The output file is as SEG extension and ODC extension.
 
Regarding to the coordinate values, I could handle these type of data and replace them using seismic unix. It worked perfectly some time ago (I mean, I replaced decimal degrees and/or arcseconds values to UTM values and load them into OD) in a desktop, but I recently tried and doesn't work (in my laptop). I mean, the file has the transformed UTM values and it is ok but, I can't load it into the OD. Probably now I'm missing something about the transformation process (because I'm at sea out of the office) and the produced SEG-Y file has something wrong, or my laptop is so "weak" that it's not possible to load it in OD as 3D. One thing that I observed is that the SEG extension (sonarwizmap file output) is recognized by OD, and moreover I can read and load with decimal degrees coordinates but not display it. I will do the transform process carefully and with ease at the office in my desktop and see what happens. However, I send you my data and see if you can work with it, I expect that my SEG-Y file works perfectly in OD but I would like a second opinion. Also, because here the sea conditions are very rough near the shore, I need a swell filter and this is a good opportunity to try the OD swell filter, what you announce recently.
 
Cheers,
 
Gery.> Date: Mon, 24 Nov 2008 09:37:59 +0100> From: Bert.Bril at opendtect.org> CC: gamejihou at hotmail.com; users at opendtect.org> Subject: Re: [Users] Loading SEG-Y files with decimal degrees> > Hi Gery,> > > I want to load some SEG-Y lines with decimal degree values as> > coordinates (sx,sy). How could I load them in OD?. I've recently> > tried but with no succesful. They are scaled by 10 000. Any hint is> > very grateful.> > You have the first SEG-Y file I've ever heard of actually using this> option. Indeed, it's in the SEG-Y standard, but:> 1) the definition is even harder to understand than the rest of the standard> 2) In the end, we all work with rectangular coordinates anyway> 3) If we'd have to support everything described in the standard, then it> would be even harder for anyone to ever read or write a SEG-Y file> > A I think we're already quite far in supporting all kinds of quirks> thought up by the 'data managers' that thought up SEG-Y, so we leave it> to any plugin builder to make the 'perfect SEG-Y' read and write. In the> mean time, I've now added a warning that we don't support this (which> will be in the next development release).> > I would try the following:> 1) You may get away by simply defining a different coordinate scaling so> that you'd get something that is comparable to meters, sort of.> 2) See whether there is a processing package (Madagascar?) that can> process the file and output a SEG-Y file that's more common.> > > Regards, Bert> > -- > -- Bert Bril / OpendTect developer at dGB> -- mailto:Bert.Bril at opendtect.org , http://opendtect.org
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