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Abstract
In this seminar , the details information about the geographical databases which are useful for storing the spatial locations ,the way in which the geometric information is given in detailed . The application and the representation of the geographic data is given here.
One of the application of the geographic data ie Global Positioning System ,which
deals with the spatial location ,is very important issue nowadays . In modern age the GPS is playing a vital role in military purpose, information broadcast system and locating vehicles.
In this seminar ,the broad overview of GPS along with its operation is explained including the characteristics of GPS receiver ,its uses.
Keywords
-Geographical Database – Geometric Information – Geometric Data – Global Positioning System – GPS Data – Time And Position –Importance of GPS
Geographical Database
Database
If we want to define the Database in a very simple language then we can say that the database is the system which stores something in it.It stores the data and various other important information in it.The database works with a proper co –ordination and thereafter forms the database system which stores the information in it and thereafter whenever required that information can be obtained very easily . The data which is stored in the database can be easily transported to the different location and it remains safe for a longer time in it,also the information is never corrupted in the database system .This database is playing a vital role in the computer storing devices,it has made a revolution in the field of storing data.
In the past years when any information was gained then it was not possible to store it inside the system ,so it became very tedious job of recollecting that data again and if we want that data to be stored then we have to do it manually . So we have to along the the recorded data for the system wherever we want that data.But after the development in the database , the data can be easily retrieved from the system because the system is equipped with the database system.This database system is very important in this way .
The information is stored in the database and it can be recollected easily with the help of the database management system . This information is mobile and can be easily transferred from one place to another and can be easily gained in the other system .This database system manages whole of the data and information.
Database systems are designed to manage large bodies of information .The management of data involves both the definition of structures for the storage of information and provision of mechanisms for the manipulation of information .In addition ,the database system must provide for the safety of the information stored , despite system crashes or attempts at unauthorized access.If data are to be shared among several users,the system must avoid possible anomalous results.
DBMS (Database Management System ) consists of the collection of the interrelated data and a set of programs to access those data . The collection of data , usually referred to as the database , contains information about one particular enterprise .The primary goal of a DBMS is to provide an environment that is both convenient and efficient to use in retrieving and storing database information .
Modern Database
The modern database is very complex and is very hard to design because it requires many complicated design to satisfy the query being asked by the user to the system . Many changes have been made in the past database because the database was having some drawbacks in them ,so the total care was taken in the modern database that the eradication of the negative points of the old database should be taken into consideration . The old database was having the drawback of storing the information with the unnecessary redundancy and does not allow the retrieval of information very easily. So the new type of the database system was developed which was called the Relational Database System .
The database which are commonly used nowadays are SQL,Asp,Java and Oracle ,etc .All these are the commonly used database system used and all of these are used in different manner and they work in total different manner with each other . This databases work mainly on the basic principle of storage and retrieval of the data.
Today in the modern database we are having the complex structure of storing the data and the information because they store the data in the indexed or the hashing manner so that the data can be easily retrieved from the database such that very less time is required to retrieve the data from the database.In the previous version of the database if the data is more in the database the system would go in the infinite loop such that the database would crash or will become distorted . Nowadays the database work on the bases of the pointers such that the redundancy of the data is not required here and we can easily point to the required data and can easily gained from the system . No extra storage is required here . The modern database is very good option nowadays for the storing of the data in a safe manner.
Geographic Databases
Spatial databases store the information related to the spatial locations , and provide support for the efficient querying and indexing based on the spatial location .For Example,suppose that we want to store a set of polygons in a database ,and to query the database to find all polygon s that intersect a given polygon .We cannot use standard index structures,such as B-trees or hash indices, to answer such a query efficiently .A spatial database would use special-purpose index structures.such as R-trees for the task.
Two types of Spatial database are particularly important:
Design databases,or computer-aided-design(CAD) databases,are spatial databases used to store design information about how objects-such as buildings,cars,or aircraft-are constructed,Other important examples of computer – aided – design databases are integrated –circuit and electronic-device layouts.This database is very important for the storing of the big structures so this database has to take utmost care that the data should be stored carefully and no error should occur . This complex data should also be stored for a long time and that too with the compete accuracy and this data should de easily transmittable also .
Geographical databases are spatial databases used to store geographic information such as maps.Geographic databases are often called geographic information systems. This databases store the maps and the geographical locations in it .All these information is important is very important for the military purpose and the vehicle driver .All the information and the data are stored in the places like the satellite so that it can be transmitted to the user whenever so that he can know where am I ? This data is important for him because this information is required to him in emergency , so the data in the database should be stored safely and this information should be easily transmitted so the data should be easily transmittable and it should be easily decoded and encoded at both the receiver and the transmitter side. This database has got a vital role in the military purpose ,for which it was developed firstly.
GPS Prerequisite
Representation of the Geometric Information
Figure which is shown below illustrates how various geometric constructs can be represented in a database , in a normalized fashion .We stress here that geometric information can be represented in several different ways,only some of which is described.
A line segment can be represented by the coordinates of its endpoints.We can approximately represent an arbitrary curve by partitioning it into a sequence of segments. To allow the use of use of fixed – size tuples , we can give the curve an identifier ,and can represent each segment as a separate tuple that also carries with it the identifier of the curve .This representation is useful for two – dimensional features such as roads ; here , the width of the road is small enough relative to the size of the full map that it can be considered two dimensional . For a map database , the two coordinates of a point would be its latitude and longitude .
We can represent a polygon by listing its vertices in order , as shown in the figure.The list of vertices actually specifies the boundary of a polygonal region.For simplicity ,we consider only closed polygons – that is ,polygons where the starting vertex in the list is the same as the ending vertex in the list.The interior of the boundary forms the polygonal region.
In an alternative representation , a closed polygon can be divided into a set of triangles as shown in figure.This process is called triangulation , and any closed polygon can be triangulated . In a manner similar to the representation of curves ,the complex polygon is given an identifier ,and each of the triangles into which it is divided carries the identifier of the polygon.Complex two-dimensional features bounded by curves , such as circles , can be approximated by polygons.
The triangulated representation is designed to be stored in the first-normal-form relational format . Non – first-normal-form representations, such as ones representing a polygon by a list of vertices or edges ,are also used in practice , where supported by the underlying database.Such list-based representations are often convenient for query processing.