Fig. 4From: Orientation Maps in V1 and Non-Euclidean GeometryPlot of the real part of a Helgason wave, with the exponential growth factor deleted: in the darkest regions the real part of the scaled wave vanishes, and in the brightest regions it is equal to one. Given the formula for \(e_{\omega,b}\), this plot also gives an idea of the argument as a function of z; notice that the argument is periodic when restricted to any geodesic whose closure in \(\mathbb {C}\) contains the point of −1 of B Back to article page