Geologists and earth scientists often have to use seismic files in their studies and various reports. The Seismic Traces palette was designed to allow professionals to examine traces in imported CGM files.
To perform any operations on Seismic Trace objects they must be selected. If Seismic Trace objects are grouped, they have to be ungrouped.
Choose Window | Palettes | Seismic Traces.
If a trace does not contain seismic data, no wiggle or background image creating can be performed on the trace. Such a trace might be imported from a CGM file with a background image already created; however, if the user erases that background image using the Purge button, it is only possible to recreate the background image via the Undo command. Refrain from performing background image operations on traces that do not contain seismic data.
The following icons are used to control the display or convey information regarding seismic traces:
Click this icon to display wiggles; click again to hide wiggles
Click this icon to display background image; click again to hide background image
Click this icon to adjust wiggle display accuracy
Click this icon to select all trace objects on current page
Icon indicating that all selected traces have seismic data
Icon indicating that only some of the selected traces have seismic data
Icon indicating that none of the selected traces have seismic data
Click Apply to apply any changes to the selected traces. Click Purge to purge all wiggles.
Group of traces in their original representation (linear approximation)
After changing colors and resampling method (replicate points)
To help better display dense plots Canvas X Draw can try to adjust accuracy with which to display wiggles. This will lower the exactness of the display but will help creating a clearer picture. The adjusted accuracy feature is triggered (if selected) when the magnification is below 100%.
Dense plot displayed without
Same fragment with adjusted
Another way of visualizing seismic data can be accomplished by creating a background image in which color is directly derived from the data. The image representation of the data is created by assigning colors to maximum, minimum, and 0 value of the data. All other data values fall in positive (between maximum value and 0) and negative (between 0 and minimum value) ranges, number of which is set by the user. The same is done with the color space between colors assigned to maximum, minimum, and 0 values. Each range of values is then assigned a color that will represent the range in the image. Colors can be later interpolated between neighboring traces to create a smoother image.
A color legend can also be created. The number of notches on the legend can be set by entering values in the Positive steps and Negative steps fields. The maximum number of notches is 20.
Click Apply to create a new image from data contained in selected traces using current options. Click Purge to erase the image already created for the selected traces.
The following images show image representation of the same fragment of data using different color ranges.
If the majority of the data is concentrated within a narrow range of values as compared to the full data range between maximum and minimum data values, the image created will appear blank since the data will be assigned only a few colors from the available spectrum. If this occurs, you can obtain the histogram of data contained in the traces and then set a window of values within which image colors will be scaled. All values falling outside this window will be assigned a minimum or maximum color.
Image created with colors scaled to full data range
To address this problem, you should obtain the histogram of the data by selecting traces and clicking the Update button. Then, you set a window of values by entering a window of values and then clicking Set. You would then select Histogram’s amplitude window from the Color scales to menu. Click Apply.
You can also set the limits by dragging sliders beneath the histogram. In the image to the left, the window limits have been set at -10.5 and 10.5. The resulting image will look much more vivid.