Maps are visual expressions of positions of the earth’s surface. Features are depicted using various combinations of points, lines and standard symbols. Maps have traditionally been produced in graphics or hard copy form. Today most mapping is then processed using computer aided drafting and design (CADD) system to develop softcopy maps which are stored within a computer. It can be analyzed, modified, enlarged or reduced in scale, and have their contour intervals changed while being viewed on the monitors of CADD systems. Different types or “layers” of information can also be extracted from digital maps to be represented and analyzed separately, and softcopy maps can be instantaneously transferred to other offices or remote locations electronically. They can be printed in hard copy if desired. Softcopy maps are indispensable in the development and operation of modern Land Information Systems (LIS) and Geographic Information Systems (GIS). This article addressed digital base mapping methods. It discussed the control survey, which is the spatial foundation of the base mapping, It also discussed digital mapping methods using graphic digitizing methods, followed by aerial photography and processes necessary to create a photo-geometric base map.
Keywords: Digital Maps, Geographic Information System, Survey Controls
