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Applies Automatic Gain Control (AGC) to a 3D seismic volume by computing a spatially varying gain function G(t) = 1/RMS(F(t), W), where W is a user-defined window in three dimensions (inline, crossline, and time). Each output sample is scaled as F_agc(t) = G(t) * F(t), normalising amplitude levels across the volume and compensating for geometrical spreading and absorption losses.
Use this module for post-stack display balancing and quality control. Because AGC destroys true relative amplitudes, it should not be applied to data intended for AVO analysis, impedance inversion, or any workflow that requires amplitude preservation.
Input and output 3D seismic volumes in SEG-Y format. Both must share the same geometry (inline/crossline ranges, sample count, sample interval).
Path to the input 3D SEG-Y file containing the seismic volume to be gain-corrected.
Path for the output SEG-Y file where the AGC-corrected 3D volume will be written. The file will have the same geometry as the input.
Selects the gain computation method. RMS-based AGC computes the gain from the root-mean-square amplitude within the window, which is robust against isolated amplitude spikes. Other available types may use instantaneous or mean absolute value calculations.
Defines the number of traces that constitute one inline section for the purposes of the AGC computation. This must match the actual number of crosslines in the 3D grid. An incorrect value will cause the spatial gain windows to be misaligned with the data geometry.
Lateral smoothing window size in the inline direction, expressed in number of traces. The RMS gain is computed over this many consecutive traces within each inline section. Larger values produce smoother lateral gain variations.
Lateral smoothing window size in the crossline direction, expressed in number of sections. Controls the spatial extent of the 3D gain across sections. Setting this greater than 1 enables true 3D AGC, which can suppress acquisition footprint by averaging gain across multiple inlines.
Vertical (time) window size in samples over which the RMS amplitude is computed at each trace location. Larger windows produce slower, smoother gain changes with depth; smaller windows react more quickly to amplitude level changes. Typical values range from 25 to 250 samples depending on the target frequency content and desired AGC aggressiveness.