GEOREFERENCING OF TOPOGRAPHICAL MAPS USING THE SOFTWARE ARCGIS PUBLISHEDMihai Valentin Herbei, Valeria Ciolac, Adrian Şmuleac, Eleonora Nistor, L. Ciolac
The digital map must be built by using all the resources available based on a rigurous analisys of their content and the costs involved, having the purpose of reaching the necessary quality under conditions of maximum efficiency. Each data source implies the existence of specialized software which will bring that data in a digital map format, starting with insuring the necessary equipment, going through the technological problems and data conversion and ending with the proper training and preparation of the personal. Before using spatial data in a Geographical Information System it is necessary to define spatial reference system which can establish with maximum accuracy the corresponding positions from earth. This can be done through a process called georeferencing process which can identify the ellipsoids and cartographical projections simulating the real space. The georeferencing process implies framing of a plan representation into a reference system called location. For georeferencing a map we need at least two pieces of information: a series of points easily identifiable on the map whose location (latitude and longitude, rectangular coordinates) is precise (here the principle is: “the more, the better”) and the projection system where the original map on paper was made. The georeferencing process of the topographical maps based on known coordinates represents the most ordinary process of georeferencing a scanned map. This type of georeferencing process is used when we can accurately find the positions of the points on the surface of the map (usually a topographical map. During the time in Romania there have been used more projection systems, and the one used from 1971 until the present is Stereographical Projection 1970 on unique secant plan based on Krasowsy ellipsoid. Before the georeferencing process we must define the Romanian National Projection system into a CAD / GIS software. The parameters of this projection which will be used to input in the used software are: Code: Stereo 70; Description: Stereographical Projection 1970; Coordinate System Type: Geodetic; Datum: Pulkovo 1941 Russia (GIS and former USSR Teriritories); Oblique: Stereographic; Northing: 500000, Easting: 500000; Projection Parameters: Origin latitude: 46d , Origin longitude: 25d; Scale reduction: 0,9998.
maps; georeferincing process; coordinates; scaning; transformation