The Global Positioning System (GPS) and Geographical Information System (GIS) works simultaneously for many purposes like vehicle tracking, locating any object, tracking, navigating, mapping and timing. So mostly this technology is widely used for determining the position of an object and measuring distance. However, the whole technology is based on maps. Maps taken by satellites and then the application of GIS technology make the whole process successful.
The GIS technology generally uses digital information with the help of digitized data creation methods. By this digitized method a map is converted into a digital format through the use of a computer aided drafting (CAD) program. Any particular place is marked by its longitudes, latitude and elevation by co-ordinate points. In this way digital satellite images are analyzed and the data in map form represents real world objects with digital form.
In order to locate the exact position of an object there are two kinds of maps are used:
Raster Maps : These are digital maps prepared from a various maps by using scanner also produced from any vector map and any other kind of satellite images. These are difficult to edit without the help of a graphic editor but can be easily converted into printed forms. These maps are made by scanning different maps and hence need perfection otherwise can generate errors.
Raster maps are able to show some of the best features with correct inputs. They are even capable of indicating some of the very small details. Here the data types contain several rows and columns of cells and each cell consists of a certain value. Each cell only contains a single value and so provides a very less storage space. However, it can be extended and each square shape cells are marked by a unique cell value. For example each cell represents a pixel area with a unit square areas of earth surface.
Vector Maps : In this case the data types are prepared by using geometric points, lines, coordinates, polygons etc. for representing any particular object. This contains real database with complete information such as name of the place, intersection points with latitude and longitude. In this way they provide the exact location of an object.
The most important aspect of vector map database is that it can contain any kind of data, which can be later modified, edited or even deleted depending on the vector format of the application. So vector maps with AVL software is one of the principal aspect in GPS and location based service.
While zooming a particular area, only some important details are shown in the map and small details don’t come on the screen; this provides fastest redraw time. Again as soon as one starts zoom in more details are shown. As all vector maps are based on latitude and longitude, these provide more accurate information, so that the GPS software can easily identify the location of an object.
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