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InlDip=Gx/Gt
CrlDip=Gy/Gt
The InlDip in a point (balck circle) is the ratio of the inline, x, component of the surface normal to the t component of the surface normal, G (black vector) and therefore a measure of how much the implicit surface (green line) is dipping relative to the horizontal (blue line).
Estimate surface normal ├ G┴⇀=[Gx,Gy,Gt ] directly from seismic for every seismic sample.
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