Why is there a need for georeferencing in GIS?
	n Maps are a common source of input data for a GIS.　 Often input maps will be in different projections, requiring transformation of one or all maps to make coordinates compatible. GIS are used for projects of global or regional scales so consideration of the effect of the earth's curvature is necessary. n Monitor screens are analogous to a flat sheet of paper, and need transformations from the curved surface to the plane for displaying data.