The similarity maps show the spatial stratification of the quantitative similarities that result - always according to the preselected similarity measure (RIV, WIV[1] etc.) - between a preselected atlas point ("reference point") and the remaining N-1 measuring points of the respective atlas grid. The reference point is selected by clicking (or activating) the polygon in question, whose surface remains white subsequently. The remaining N-1 polygons are colored according to the specifications of two interval algorithms (MINMWMAX and MEDMW) and using 2, 4, 6, 8, 10 or 12 color levels taken from the solar spectrum.