Displaying polarization fields with line integral convolution

The method of line integral convolution, introduced by Cabral and Leedom in 1993, can be very useful for displaying polarization fields. The method creates a texture which is aligned with the direction of the polarization. When using it to view polarization on the sphere, such as with the Cosmic Microwave Background (CMB), this method creates a smooth texture which: represents both magnitude and direction of the polarization field, can be easier to interpret than discrete-lines-on-a-grid, can be correctly projected as easily as CMB temperature data, and can easily be overlayed on CMB temperature data. This method has been implemented as part of the Healpix code.