From Wikipedia, the free encyclopedia HEALPix H=4, K=3 projection of the world. The lines on the map are a graticule of latitudes and longitudes. The grid used by HEALPix and its subdivision of the sphere in four different grid refinements. HEALPix (sometimes written as Healpix), an acronym for Hierarchical Equal Area isoLatitude Pixelisation of a 2- sphere , is an algorithm for pixelisation of the 2-sphere and the associated class of map projections . [ 1 ] The pixelisation algorithm was devised in 1997 by Krzysztof M. Górski at the Theoretical Astrophysics Center in Copenhagen, Denmark, [ 2 ] and first published as a preprint in 1998. [ 3 ] [ 4 ] Projection and pixelisation [ edit ] The HEALPix projection is a general class of spherical projections, sharing several key properties, which map the 2- sphere to the Euclidean plane . [ 1 ] Any of these can be followed by partitioning (pixelising) the resulting region of the 2-plane.…