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 on Automatic Gain (AGC).
- Type a name for the process and click OK.
Configuring the AGC Process
- In the Details Panel, select a Volume.
- Select the Gain function:
- Arithmetic mean within a window
- Median within a window
- Geometric mean within a window
- RMS within a window
- Median Mean: Specify the Percentage trim value.
- [Optional] Enter in the Clip scalars.
- Enter the Window length (ms) and Window overlap (%).
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.
Note: To reverse the gain, use Volume Maths (Simple) process to divide the gained functions by the scalars.