Fig. 3

Pattern gradient lattices obtained with the GPA operation. Left: First helical structure from the tip of the spiral with the respective vector lattice superimposed on the image. In the inset at the top left, two generic vectors are shown with the criterion for measuring their respective phases from their horizontal baselines (applied to all asymmetric vectors (in blue)). In the inset on the right examples of symmetric vector pairs (in red) are shown for the target pattern which is completely symmetric (note that, for this particular symmetric pattern, \(V_A\), as defined in equation 3, is null). Right: at the top, is shown the lattice gradient for a typical correspondent random pattern (in the inset picture). At the bottom, is shown a typical lattice gradient for phase turbulence (in the inset it is the correspondent turbulent pattern).