Spherical gradient operator
Shigang Li · IEEJ Transactions on Electrical and Electronic Engineering · 2013
Abstract In this paper, a spherical gradient operator is proposed that computes the gradient from a discrete spherical image with irregular pixels. In contrast to the conventional methods which approximate spherical pixels as regular hexagons, the proposed method can cope with irregular pixels and compute the gradient vector relative to the camera coordinate system directly. We also show that the conventional Sobel operator can be treated as a special case of the proposed approach. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.