Module: SEG-Y Wizard ()

Description:

The SEG-Y Wizard tool allows you to control the import of SEG-Y post-stack data as it is being loaded into prior to conversion into LDA file format.

You can use it to:

There are many variations in SEG-Y files, particularly in where key bits of info are stored in the file header and more importantly in the trace header. Unfortunately, it is not always possible to determine algorithmically where certain info is stored, and sometimes human intervention is required to provide information about the data.

With the SEG-Y Wizard, it is possible to provide this info, allowing the SEG-Y data to be correctly extracted from the file.

Another important capability of the SEG-Y Wizard is the ability to set the coordinates associated with the corners of the survey. For many purposes, you'd like to know where the survey is actually located with respect to geo-referenced coordinates. Normally there is some information in the file about this, although not always in the same place, or possibly not interpreted correctly. The Wizard's Coordinate setting panels lets you adjust the coordinates associated with the corners of the survey.

When you start to load a SEG-Y data file, asks if you want to start the SEG-Y Wizard. If you click "Yes", the SEG-Y Wizard starts up. (If you click "No", the older SEG-Y file reader is used.)

If a file with the same name and the extension .lda already exists in the same directory, you will be asked if you want to overwrite the file. If you answer yes, the file is overwritten and the Wizard is displayed. If you answer no, the Wizard is not displayed and the file is not loaded.

You can use the "Next" and "Back" keys to navigate between the panels of the Wizard, or you can use the left navigation pane to go directly to a specific panel.

When you click the Finish button on the SEG-Y Wizard, your SEG-Y file will be converted to LDA format (this may take some time for a large file) and the default seismic visualization modules will appear in the Project View. These include inline, crossline, and time slices as well as seismic axes.

Textual Header

This panel displays the text header of the SEG-Y file. You can specify the text encoding: ASCII or EBCDIC. If the displayed text is unreadable (garbage characters) using one encoding, try using the other.

Binary Header

This panel displays values from the binary file header. By default only the most common values are displayed. However, you can request that all values be displayed by clicking on the All values radio button.

If the values shown in this panel do not seem reasonable, try switching the byte order from Big Endian to Little Endian (or vice versa) using the radio buttons at the top of the panel.

You can modify the start byte position for certain information in the file. Sometimes this is necessary if the file is not interpreted correctly by default.

The tooltip for the data sample format code provides valuable information regarding the format code values and their meanings.

Trace Header

This panel displays values from the trace header. By default only the most common values are displayed. However, you can request that all values be displayed by clicking on the All values radio button.

The header for trace 1 is displayed by default. However you can use this panel to display the info for any trace by using the slider and/or the numeric field to specify the trace number.

You can modify the start byte position for certain information in the file. Sometimes this is necessary if the file is not interpreted correctly by default.

The Format column allows you to specify the storage format (8-, 16-, or 32-bit integer, IBM float or IEEE float) for each item in the trace header.

When you click "Next", the Wizard will automatically scan all of the trace headers to determine (for example) the ranges of the inlines and crosslines. Press the Abort Scan button to stop this operation.

Inline/Crossline/TimeLine

This panel allows you to correct the range and step values if they were not interpreted correctly by the SEG-Y file reader.

Coordinate Setting

This panel allows you to review the survey's geographic coordinates extracted from the file and, if necessary, correct them.

Preview

This panel displays a 2D preview of your seismic data. You can specify the first trace number as well as the number of traces to display.

Data Conversion

This panel allows you to convert your data to one of several output formats: 8-bit signed or unsigned, 16-bit signed or unsigned, 32-bit signed or unsigned, or float. The format shown initially is the original data type of your input data.

You can specify that the minimum and maximum values be determined from the data itself, or you can supply these values yourself. Normally these values are only important if you are converting to a data type that has a smaller fixed range of values. You may find the min and max values in the text header.

The Add Standard Visualization Tools check box allows you to turn off automatic generation of the default seismic modules. By default, the following modules are connected to your data set: Bounding Box, Seismic Axis, Inline, Crossline, Time Slice, ROI Box Seismic, and Cropped Volume. These latter two objects have their visibility in the viewer toggled off initially because volume rendering can be expensive.

TIP: If the slices appear to be low resolution data, the LDA Main Memory may be set too low to allow loading full resolution data for all slices. You can try turning off some of the slices or adjust the Main Memory setting higher on the LDA tab of the Edit/Preferences dialog.