 Often this has to be done when layers created from adjacent map sheets are joined together.Rubber-sheeting is necessary because the imagery and the vector data will rarely match up correctly due to various reasons, such as the angle at which the image was taken, the curvature of the surface of the earth, minor movements in the imaging platform (such as a satellite or aircraft), and other errors in the imagery.Rubbersheeting is a useful technique in HGIS, where it is used to digitize and add old maps as feature layers in a modern GIS.