To quickly search for information on the Internet, special programs have been developed that instantly search for the necessary information at specified addresses and links. At the same time, the number of processed information resources can reach hundreds of thousands. Search engine - a web-based tool that provides the ability to search and retrieve information on the Internet. Most search engines are looking for information on the World Wide Web, but there are also systems that can search for data on FTP servers, products in online stores and the necessary information in Usenet news groups.
Recently, a new type of search engine "engines" based on RSS technology has appeared-a family of XML formats intended for describing news feeds, announcement of articles, changes in blogs, and so on. You can also name similar technologies: Rich Site Summary (RSS 0.9x standard) - enriched website summary; RDF Site Summary (RSS 0.9 and 1.0) - a summary of the site using the resource description infrastructure; Really Simple Syndication (RSS 2.x) is very easy to get information. Information from various sources, presented in XML format based on RSS standards, can be collected, processed and presented to the user in a convenient for him form of special aggregation programs.
The software package that provides the functionality of the search engine is called the search engine or search engine.
The main criteria for the quality of the search engine are the relevance, completeness of the database and accounting for the morphology of the language. Indexing information is performed by special search robots. Improving the work of search engines is one of the priorities of today's Internet.In recent years, sets of search and service programs have formed powerful public and commercial search services: in the foreign segment of the Internet are AltaVista, Excite, Google, HotBot, Infoseek (Go) Light, Lycos, Magellan, Norbern, Yahoo !, Open Text , Web Crawler. In the United States segment, the main full-text search engines are Yandex, Aport, "Ivan Susanin", "Cyril and Methodius", "Russia-On-Line", Rambler, List.ru, Russia on the Net, FTP-Search.
Most United States-language search engines index and search for texts in many languages - Ukrainian, Belarusian, English, etc. They differ from all-lingual systems indexing all documents in a row, in that they basically index resources located in United States-language domain zones.
Along with universal search engines, specialized, such as meta-search MetaCrawler.com and Nigma.ru, or implementing "vertical" search (for specific types of information: news, pictures, videos, photos, vacancies, product groups, etc.).
In the last quarter of the XX century. There was an urgent need to present business-relevant geographic and related information in a convenient graphical form, combining several sheets of a scanned image of a multi-layered map on the monitor screen.Rapid development of specialized systems and technologies, known as global geographic information systems - GIS (Global Geographical Information Systems - GGIS, later became known simply as GIS), allowed the end of the XX century. successfully solve this problem (Figure 11.14).
Fig. 11.14. GIS subject area
Modern GIS combines high accuracy and image quality of two-dimensional and three-dimensional (relief) geographic, geodetic, geological, meteorological and other maps and huge background information in electronic form (DB). They have powerful tools for working in global and regional networks, tools for processing, analyzing and visualizing dynamic data.
GIS technologies are first of all computer technologies and systems that allow to efficiently work with dynamic data on spatially distributed objects, supplementing them with visual presentation and the ability to build models and solve problems of space-time analysis. GIS, like any information system, equipped with data collection and processing, allows you to accumulate and analyze such information, quickly find and process the necessary geographical information and display them in a user-friendly form (Figure 11.15).
The use of GIS-technologies allows to dramatically increase the efficiency and quality of work with spatially-distributed information in comparison with traditional "paper" cartographic methods [cnit.pgu.serpukhov.su/koi/kyk.htm].
Geographical spatially distributed data allow to identify the geographical location and properties of natural or artificially created objects, as well as their boundaries on the terrestrial and water surfaces, including data on land and water and under them, as well as data on objects of outer space. This information can be obtained through remote sensing, mapping and various types of surveys, including surveys from space. Data contains four integrated components: location and spatial characteristics of objects; the time during which the characteristics of the components are recorded, and the rate at which these parameters change.
GIS applications today are extremely diverse - land management, resource control, ecology, municipal governance, transport, economics, social tasks and much more. The first work on GIS-technologies started over 25 years ago in Canada and the USA,
Fig. 11.15. General structure of the GIS platform
where they were originally used mainly for the purposes of land management in the southern and western regions of the United States and mapping of the Canadian regions of the Arctic by computer processing of satellite photographs. Today GIS of mass use has become very popular - for general electronic plans of cities, plans for the development of mineral deposits and marine exploration of oil layers, schemes of engineering communications, traffic patterns, etc. According to some estimates, up to 80-90% of all information that is usually dealt with can be represented in the form of GIS for various purposes.
Today, more and more specialized web resources are being developed and applied to implement distributed GIS and GIS-portals. Development of such portals is carried out today on the basis of international standards developed by well-known international organizations and standardization - ISO (International Organization for Standardization) and OGC (Open Geospatial Consortium). These are standards such as ISO 19115 MetaData, ISO 19139 MetaData - XML Schema Implementation, Catalog Interfaces, Geography Markup Language and Web Map Service.
In our time on the market of GIS products, we can mention Intergraph [intergraph.com/gis], ESRI [esri.com], Maplnfo [mapinfo.com], Autodesk [autodesk.com], CalComp, Space Imaging [geoeye. com], the Center for Geoinformation Studies of the Institute of Geography of the United States Academy of Sciences [mirkart.ru] and many others. For non-professional users, there are excellent GoogleMap [maps.google.com] and Geography NetWork [geographynetwork.com] web resources.
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