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The AVO section contains modules for Amplitude Versus Offset analysis workflows. These tools convert offset-domain gathers to angle-domain, apply angle-based muting, create partial-angle stacks, and decompose amplitude behaviour into AVO attributes using the Shuey approximation. The recommended processing order is: NMO correction → Vrms to Angle → Mute by Angle Range → AVA (or Angle Stack). Angle gather quality directly controls the accuracy of all downstream AVO attributes.

Modules in this section

Vrms to Angle — Converts offset/time gather traces to incidence angle using a velocity model. Produces an angle gather required as input for all subsequent AVO modules.

Mute by Angle Range — Zeros gather data inside or outside a user-defined angle window. Use to exclude near-angle noise or far-angle non-linearity before AVO analysis. Supports linear taper at the mute boundary.

Angle Stack — Stacks NMO-corrected traces into common-angle partial stacks over a configurable angle range and step. Produces near, mid, and far stacks suitable for AVO crossplotting and inversion input.

AVA — Computes Intercept, Gradient, and optionally C-term volumes by fitting the Shuey 2-term or 3-term approximation sample-by-sample via SVD regression. Requires NMO-corrected gathers and a co-registered angle gather. Limit Max angle to 30–35° for reliable Shuey validity.

Orthogonal Polynomial Transform — Decomposes offset-dependent amplitudes using Legendre polynomials. Outputs the transform gather, reconstructed gather, and residual gather. Configurable approximation and reconstruction orders (1–8).