Automatic Gain (AGC)
The Gain process can be applied to any volume. It generates two result volumes:
- a volume with a scaling applied to the trace amplitudes
- a volume containing the scales applied (with suffix _scalars)
Use the *_scalars volume with a Volume Maths (Simple) process to:
- Apply the same gain to a different volume (multiply by scalars)
- Remove the gain from the scaled volume (divide by scalars)
When applied to gathers, lateral smoothing can be applied to the scalar calculation to avoid the impact of noise.
Note: For data-independent gain functions, use the Gain process instead.
Create an Automatic Gain (AGC) process
- In the Control Panel, open the Process tab.
- At the tab header, click the Add icon, and select New Process.
- Scroll down, and double-click Automatic Gain (AGC).
- Type a name for the process, and click OK.
Configuring the AGC Process
- In the Details Panel, select a Volume.
- Select a Gain function:
- Smoothed absolute values
- Smoothed root-squared values
- Smoothed instantaneous amplitude
- Windowed arithmetic mean
- Windowed geometric mean
- Windowed RMS
- Windowed median
- Windowed median mean
- [Optional] Enter in the Clip scalars.
- Enter the Window length (ms) and Window overlap (%).
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Lateral Smoothing: Smooth the calculated gain over a sliding window before applying. Applies to gathers and panelled data only.
- Set this to 0 for stacks and other non-gather volumes. Lateral smoothing is not applicable to non-panelled data.
- Radius (traces): The size of the smoothing window.
- Trim (%): The percentage of outlying samples to discard from the smoothing window.
- Bulk scale: Set a scale to apply to the whole volume, on top of any data-dependent gain.
Note: To reverse the gain, use Volume Maths (Simple) process to divide the gained functions by the scalars.