geopsy.org

Posted: **Tue Apr 21, 2009 8:51 pm**

Hello,
I'm importing data to geopsy for H/V analysis and can only get the component for each trace set correctly by manually editing the table after import. Is there a way to get geopsy to "see" the component correctly during import?

These data are .sac, though I could use segy or other format if that would help. I'm creating sac files with the PASSCAL software (segy2sac). I suspect that sac format includes a component field in the header and that the PASSCAL software is not writing this header field in the same way that geopsy expects (perhaps it is not writing it at all). For these data, the component is specified by the last number in the filename, before .sac. For instance, 08.177.22.13.33.938C.1.sac is the vertical component, 08.177.22.13.33.938C.2.sac is north, and 08.177.22.13.33.938C.3.sac is east.

Is there a way that geopsy can use this information? Or is there another way that I can avoid having to manually set the components for my data (easy for one or two sets of signals, but very time consuming for a larger number). I tried changing 1,2, and 3 to z, n, and e, but that was not successful.

How does geopsy determine the component for imported data?

Thanks,
Seth

Posted: **Mon Apr 27, 2009 6:03 pm**

When available in a standard way in a file format, Geopsy does its best to identify components. Usually, components in SAC format are properly recognized. You can check in SAC (if you have it) the contents of component field (I can't remember its name, but it is usually obvious when you look at signal info in SAC). Geopsy looks for letters 'Z', 'N' and 'E' to match for Vertical, North and East respectively. If your files contain information about components, it would be nice to send us a file sample (of the 3 components). If it is too large, you can send them to ftp://ftp.geopsy.org with an explicit name.

In any case, there is a semi-automatic way to set components and eventually other fields. Activate a signal viewer (table -- easier for header manipulation --, map or graphic) and go to menu "Edit/Set header". In this dialog box you can enter any script to transform the header data (sampling frequency, T0, signal name, coordinates,...). When clicking on 'Apply', the script is executed once for each signal of the current viewer. You can eventually define variables that persist from one signal to the other.

To change components from patterns in file names, here is an example:

Code: Select all

// Extract one digit at the end of file name, just before extension.
a=left(right(ShortFileName,5),1);
Component=if(a==1, "Vertical",
          if(a==2, "North",
                   "East" ));

geopsy.org

getting components to load correctly when importing signals

getting components to load correctly when importing signals