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Map database management
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Map database management
Map database management systems are software programs designed to store and recall spatial information for navigation applications, and are thus a form of Geographic information system. They are widely used in localization and navigation, especially in automotive applications. Moreover, they are playing an increasingly important role in the emerging areas of location-based services, active safety functions and advanced driver-assistance systems. Common to these functions is the requirement for an on-board map database that contains information describing the road network.
When designed well, a map database enables the rapid indexing and lookup of a large amount of geographic data.
Maps are stored as graphs, or two dimensional arrays of objects with attributes of location and category, where some common categories include parks, roads, cities, and the like.
A map database represents a road network along with associated features. Map providers can choose various models of a road network as a basis to formulate a database. Commonly, such a model comprises basic elements (nodes, links and areas) of the road network and properties of those elements (location coordinates, shape, addresses, road class, speed range, etc.). The basic elements are referred to as features and the properties as attributes. Other information associated with the road network is also included, including points of interest, building shapes, and political boundaries. This is shown schematically in the adjacent image. Geographic Data Files (GDF) is a standardized description of such a model.
Each node within a map graph represents a point location of the surface of the Earth and is represented by a pair of longitude (lon) and latitude (lat) coordinates. Each link represents a stretch of road between two nodes, and is represented by a line segment (corresponding to a straight section of road) or a curve having a shape that is generally described by intermediate points (called shape points) along the link. However, curves may also be represented by a combination of centroid (point or node), with a radius, and polar coordinates to define the boundaries of the curve. Shape points are represented by lon-lat coordinates as are nodes, but shape points do not serve the purpose of connecting links, as do nodes. Areas are two-dimensional shapes that represent things like parks, cities, blocks and are defined by their boundaries. These are usually formed by a closed polygon, which are shapes that indicated an object over a map has to have a close boundary, meaning the first vertex should be same as the last vertex. (For example, to plot a square object on a map, the vertices of the polygon are numbered 1,2,3,4,1, in this order)
Another point for validation on data is the point in polygon, which helps in finding points lying outside a polygon. E.g., for a particular lon-lat coordinates in a city, if the point is intersecting the polygon in an odd number, then it is inside the polygon and a valid point; otherwise it is outside the polygon and invalid.
Map providers generally collect, aggregate and supply data in a well-defined and documented file format that is specifically intended for information interchange, e.g. Navteq uses Standard Interchange Format (SIF) and Geographic Data Files (GDF), while Tele Atlas uses a proprietary form of GDF. It is usually in a plain-text form (ASCII) consisting of fields that are easily parsed and interpreted by the various parties who will handle it. The portable format allows additions, deletions and modifications to be readily performed by simple text-editing programs.
A small number of record types are used to represent the various types of data. Each record type consists of a sequence of fields, which are either fixed length or delimited by a punctuation character such as a comma. For example, a link entity could be represented by a record of the form:
Hub AI
Map database management AI simulator
(@Map database management_simulator)
Map database management
Map database management systems are software programs designed to store and recall spatial information for navigation applications, and are thus a form of Geographic information system. They are widely used in localization and navigation, especially in automotive applications. Moreover, they are playing an increasingly important role in the emerging areas of location-based services, active safety functions and advanced driver-assistance systems. Common to these functions is the requirement for an on-board map database that contains information describing the road network.
When designed well, a map database enables the rapid indexing and lookup of a large amount of geographic data.
Maps are stored as graphs, or two dimensional arrays of objects with attributes of location and category, where some common categories include parks, roads, cities, and the like.
A map database represents a road network along with associated features. Map providers can choose various models of a road network as a basis to formulate a database. Commonly, such a model comprises basic elements (nodes, links and areas) of the road network and properties of those elements (location coordinates, shape, addresses, road class, speed range, etc.). The basic elements are referred to as features and the properties as attributes. Other information associated with the road network is also included, including points of interest, building shapes, and political boundaries. This is shown schematically in the adjacent image. Geographic Data Files (GDF) is a standardized description of such a model.
Each node within a map graph represents a point location of the surface of the Earth and is represented by a pair of longitude (lon) and latitude (lat) coordinates. Each link represents a stretch of road between two nodes, and is represented by a line segment (corresponding to a straight section of road) or a curve having a shape that is generally described by intermediate points (called shape points) along the link. However, curves may also be represented by a combination of centroid (point or node), with a radius, and polar coordinates to define the boundaries of the curve. Shape points are represented by lon-lat coordinates as are nodes, but shape points do not serve the purpose of connecting links, as do nodes. Areas are two-dimensional shapes that represent things like parks, cities, blocks and are defined by their boundaries. These are usually formed by a closed polygon, which are shapes that indicated an object over a map has to have a close boundary, meaning the first vertex should be same as the last vertex. (For example, to plot a square object on a map, the vertices of the polygon are numbered 1,2,3,4,1, in this order)
Another point for validation on data is the point in polygon, which helps in finding points lying outside a polygon. E.g., for a particular lon-lat coordinates in a city, if the point is intersecting the polygon in an odd number, then it is inside the polygon and a valid point; otherwise it is outside the polygon and invalid.
Map providers generally collect, aggregate and supply data in a well-defined and documented file format that is specifically intended for information interchange, e.g. Navteq uses Standard Interchange Format (SIF) and Geographic Data Files (GDF), while Tele Atlas uses a proprietary form of GDF. It is usually in a plain-text form (ASCII) consisting of fields that are easily parsed and interpreted by the various parties who will handle it. The portable format allows additions, deletions and modifications to be readily performed by simple text-editing programs.
A small number of record types are used to represent the various types of data. Each record type consists of a sequence of fields, which are either fixed length or delimited by a punctuation character such as a comma. For example, a link entity could be represented by a record of the form: