Maps and cartography
Already in ancient times it was important to be able to draw maps and measure the terrain in order to describe the topography of a country, decide border conditions or to set up large constructions. The oldest known map has been found in Iraq, and is from about 3800 years BC. Navigational maps were developed as a result of the great expeditions in the 1500’s. |
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| Background |
| It took a long time before systematic measuring work in order to make nationwide series of maps in Norway got started. There are very few maps from the time before The Norwegian Military Measuring was established in 1773. The first maps were made for military use. Later on the civilian objectives became dominant and Norwegian Military Measuring was re-named the Norwegian Mapping Authority. |
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| Localization and standards |
| With the GIS technology far greater possibilities of application are available for accurate localization. Nationally ”Standardized description of geographic information”, SOSI (SK, 1997) is the prevailing format (standard) for the exchange of geodata. |
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| The coordinate system of the Earth |
| If we are to find the localisation of a certain place on the Earth, we employ meridians (longitudes) and parallel circles (latitudes). The position is given as “longitude” and "latitude". The latitude of a place is the parallel running through the place, the longitude is the meridional. |
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| Ellipsoid and geoid |
| In order to make the GPS system able to measure an accurate position on the Earth, there should be an underlying framework describing coordinates and references. Geodesy is the science dealing with the form, gravitation and changing of the Earth. A geodetical system is a framework for deciding coordinates on the surface of the Earth in relation to a reference, ellipsoid and geoids. |
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| Map projection |
| The Earth is an ellipsoid (approximately globular) and the map is a plane surface. By means of the map it is possible for the user to have the terrain on the table or the data display. |
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| The UTM projection system |
| In order to give positions on the ellipsoid there is a need for a coordinate system. UTM system builds on a unique projection with a coordinate system belonging to it. Ordinarily, we talk about the UTM coordinate system and the UTM reference system. |
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