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
1. Zhukov VT Serbenyuk
SN Tikunov VS Mathematical and cartographic modeling in geography. Moscow:
Mysl, 1980.
2. Vahrameeva LA
Kartografiya.-M.: "Nedra", 1981.
3. Berlyant AM
Cartography. Moscow: Aspekt-Press, 2001.
4. Zarutsky IP, Svatkova
TG Design and production of maps. General geographic maps. M.: MGU, 1982.
5. Spikelets YU.S.V.,
Khlebnikov, TA "The technology of automated generalization" (Journal
of Geodesy and Cartography »№ 6, 2005. p.38)