using the four following animation and pictures (please note that the colors of the pictures 'PA' and 'PR' differ due to specific color post-processings):
PA[x,y] = (X and Y periodical)
PX[x,y] = (the 'X' pseudo-projection of the sphere)
PY[x,y] = (the 'Y' pseudo-projection of the sphere)
PZ[x,y] = (the 'Z' pseudo-projection of the sphere)