География и геология/ 5. Картография и геоинформатика

Магистрант гр. ГиКМ-10-1 Зулгарина Д.А.

Карагандинский государственный технический университет, Казахстан

Generalisation of Geographic Information Systems

Currently, digital cartography has a leading role in the cartographic production. At the same time play a dominant geographic information system. With GIS you can achieve far more than simply display data on the card. GIS combines the tools of conventional packages cartographic display, the functions of a thematic presentation of information based on the binding of tabular data to the addresses and streets, analysis capabilities of geographic locations, with more information on being in these places objects. This technology connects together graphics display tools, work with spreadsheets, databases and data warehouses. You can just get the information about an object by clicking it on the electronic map, or create and display a map based on the information selected in the database. And the map link with the dynamic data. Created in the GIS maps are not tied to a specific point in time. At any moment you can update the information tied to the card, and your changes will automatically be reflected on the map. And it does not need special training. However, these systems are used in automated generalization does not yield reliable results, which leads to the rapid intervention of the performer.

Generalization - an inherent property of cartographic images, even the large scale. It manifests itself in the compilation of qualitative and quantitative characteristics of the facilities, changing notions of a collective individual, abstracted from the particulars and details to show the main features of spatial distribution. All this allows us to consider the generalization as a manifestation of the process of abstraction is displayed on the map of reality. In this generalization is not only to the exclusion of the information contained in the original image, but also to the emergence of qualitatively new information on the generalized map. As the generalization more clearly appear the most important features of the object, leading patterns, the main relationship, highlighted geosystem increasingly large rank. With normal mapping on paper quality of generalization depends primarily on understanding the content cartographer (geographical, geological, etc.) depicted the essence of objects and phenomena, the ability to reflect the main, typical of their features.

The main task of cartographic generalization is a generalization of the geographical base of thematic maps in order to build cartographic database for GIS. With the development of GIS as a class of automated systems, raise the demand for improvement of methods of processing and displaying spatial information, based on cartographic data bases. There is a need to cut off that piece of information that can not be displayed according to the restrictions relating to the scale of the image and screen resolution. Thus, the task of automated generalization - the selection and compilation shown on a digital map of objects, respectively, the scale of the image, the screen resolution and features of the mapping area in order to reduce the volume and distortion when displaying the processed data, speed up the display.

Now the Republic of Kazakhstan to create thousands of nomenclature sheets of topographic maps and plans of different scales, which need updating and monitoring, which requires enormous effort and financial resources and time. For certain tasks require less detailed maps, that is maps covering large areas, and reflecting. This inevitably raises the problem of obtaining detailed, detailing the specific area of digital maps and more generalized, that is digital maps on a smaller scale.

Digital map - digital surface model formed by taking into account the laws of cartographic generalization in the accepted card projection, coordinates and heights. Digital maps are created based on the automated generalization.

At the present stage of automated generalization has several disadvantages. One of the key is to use hardware or software and hardware that requires large financial costs, the huge labor and time. Hardware and software and hardware techniques are very time-consuming, so, for example, the area of hardware unit is 9 sq.m.

Another disadvantage of automated generalization is formalizing the process of cartographic generalization in general (getting models derived scale). That is not automation of individual acts of compiler, as far as possible, the exclusion from the process of generalization of action mapper, which tend to be subjective.

Also, the lack of automated generalization is formalizing the structure of the original digital data processing cards, because the structure of digital technology, as a rule, does not contain the information necessary for automated generalization, as presented in the form of consistent and, as a rule, not a structured list of objects. The formalization of the data structure - the identification of objects digital routing or aggregates, their spatial relations (the definition of topological relationships) and the determination of the degree of importance (priorities). The process of recognizing patterns of exposure control parameters - the scale derivative of the map, especially the territory, etc.

Requires further formalization of the functions of automatic generalization, which consists in determining the types of processes of generalization for information structures based on controlling parameters. Identified five basic types of processes: the selection of map objects, the generalization of the quantitative characteristics, a synthesis of qualitative characteristics, geometric generalization and replacement of individual objects of their collective value. These processes constitute a library of functions and determine their characteristic set of formal parameters.

Based on the above set forth to solve the problem of automated generalization, that is its improvement, we propose a method of cubic splines. Under the spline is usually described as an aggregate function, which coincides with the functions of a simple nature to each element of its domain. Classical spline of one variable is constructed as follows: the domain is partitioned into a finite number of segments, each of which coincides with a spline an algebraic polynomial. The maximum degree of polynomials used is called the degree of the spline. The difference between the degree of the spline and the resulting smoothness is called the defect of the spline. It is necessary to calculate the marginal error that is acceptable for our generalization, that is find the minimum and maximum deviation of the line to achieve a minimum distortion of shape, size and area of the depicted object.

Literature

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