Source: http://www.lbschina.com.cn/forum/dispbbs.asp? BoardId = 24 & id = 2096
Abstract This article describes the basic mathematical model of GIS according to the GIS specific application example, and analyzes the nature of non-geocotent data data and the organizational method, and proposes a new point of view of the code.
Keywords gis non-geocotent data graphics coding
0. Introduction In recent years, GIS data processing technology is penetrating into the society of society at an unprecedented speed. GIS development applications in all walks of life have increased dramatically, and the professional GIS platform has a wide variety of new technologies, new ideas, and give people a feelingful. As an amateur GIS practitioner, the basic principle of GIS data processing technology and its application methods are set forth according to the industry. The point of view is to be made, please also ask the GIS hipster ax.
1. The current data object of the current GIS mathematical model GIS is limited to the geographic mapping department, based on geographic information, municipal, earth tersons, electric power, telecommunications, tap water, etc., the same applicable to GIS data processing technology, this is no doubtful Objective facts. It is worth exploring that how do the relevant departments use the basic geographic information provided by the surveying department? How do they organize their respective professional data? The current GIS data processing model is on the massive digital geographic background diagram, superimposed by the respective professional icons, then use built-in or plug-in relational databases to query the parameter records belonging to the statistical graphic symbol. Such mathematical models, the actual application effect is not ideal: the operator is painful between graphics and forms, but it has always been necessary; in addition to the expensive professional GIS platform, the application unit has to bear the same expensive relational database platform. The author believes that the basic principles of the current GIS mathematical model have to be discussed.
2. The basic structure of GIS data Sea-grade digital map is originally based on a certain scale, a certain projection (geographic coordinate system), which is saved in the geographic mapping department. It used to be in the form of a drawing, and now there is a digital map format. Probably the computer graphics processing technology is too easy to splicing, and the program designer is easy to put a large number of geographical maps, splicing into a massive digital map, as a geographic background of each GIS related industry. Such a system design method, violates the basic principles of the information processing technology of modular design. For simple geographic information, the basic data module that can be used independently, is a geographic map of each certain proportion, a certain projection band. The amount of information data of the single geographical map is quite limited, and the number of geographical splines is added to form a massive geographic background. On a small computer screen, the massive graphical data is adjusted, and the results are like the masterpiece of the impressionist, I don't know the cloud. Among the actual applications, the operator is often close to the geographic background layer in order to keep the screen. I know today, why bother. The GIS related industry is in the data initialization phase, and it is indeed possible to collect all geographical maps, including the geographic map of different coordinate systems, which can transcribe their respective industry icon arrangement pictures on the drawing or electronic map, without having to spend a lot of manpower, Materials, on-site surveys, system development cycles can be greatly shortened. The transcription process is essential because the icon specification of the surveying and mapping department is not the same, and the logical relationship between the icon is even more than the mountain. At this point, the relevant industry departments have no objection, and practical applications are also operated. However, no matter the basic principles from data processing, or the actual application angle, there is no reason to overlay the massive geographic map as the base background. Maybe someone wants to ask, the geographic map of the transcription, still often require basic geographic information as a reference background, how to dispose? In fact, this is easy to resolve, you only need to save all geographical maps in the specified hard disk directory, which is required to transfer in the superposition one by one. Obviously, such an application model, more in line with the basic principles of data processing, and computer system resources can also be greatly saved. We want to emphasize a little, whether the basic geographic infographic, or an industry icon arrangement, must follow the geographic coordinate system of the surveying department. The geographic coordinate system not only has a strict mathematical projection formula, but also a statutory standard specification. Often encounter some non-geographical designers, arbitrarily assume their geographic coordinates. Such a design method can be applied for a while, but it has brought endless problems to the future data maintenance. Your data will become "information island": It cannot be shared by others and cannot share other people information. "The map will never keep up to build", you collected the latest layout map, which is likely to be five years or even ten years ago. The geographic information of dynamic changes is to constantly repair updates in accordance with the fixed coordinate system. The geographic coordinate system is actually the basic coding dictionary of geographic information data, how do designers can assume the code dictionary with their own will. The author is not the importance of geographic professionals, understanding geographic coordinates, is completely experienced.
3. Non-geographic attribute data organizes the author identity: From internal structure, computer data processing technology can summarize the logically relational database processing model; all information data, text, numbers, graphics, images, Sounds, etc., are stored in the computer inside the computer in the form of abstract table. This is the technical issue discussed by professional-level system developers, and the author has no ability to analyze in depth. From a specific application angle, abstract or is a logical relational table database, whether you have a table data record that is imaged into an appearance, which is worth the application developers to carefully scrutinize. For the most commonly used DXF format, the internal form is standard ASCII code table data, but their external performance form is the geometric entity of the specific image. For application developers, the application operator is used, and the table record and graphic data are completely different data types, their organizational methods, and query means are completely different. Simple graphic data organization method and a simple table data organization method, no one will confuse. The organizational method of non-geographical data in the current GIS related industry, the author did not dare to share. Most application developers integrate them into a stringent table record, and perform related queries and statistics in the table database. The surface seems to be in accordance with the management mode of these attribute data. These attribute data have no exception to store in the table book without exceptionally before the computer graphics processing technology. But this is no. They are not behind the graphic symbols, but they cannot be implemented at the manual drawing phase. Today, the computer graphics technology is perfect today, you can use the implicit display, transparent superposition, etc. . That is just that non-geographic attribute data is organized, in essence, they are originally graphic data, not formatted in general. Their organizational approach is as drawing, and a strip attribute must be recorded (similar to geometric entity), and the dispersion is marked in the position where they should appear. The convenient and flexible dispersion process is only the surface form of the human-machine dialog, and the central storage is still the internal structure of the attribute data computer. For programmers, the face-to-face DXF format is still uniform, which is not two of the ordinary form data (actually DXF format data is just the application developer's data codes, the low-level data code is more complete But this is the data format facing the professional developer). For specific applicants, inquiry statistics, is their greatest desire.
4. Digital encoding in the graphic coding method, we have used to drive lightly, coding [1] may be more unfamiliar. But "information technology workers gradually realize the use of geographical location to retrieve data, the basic method of organizing and using digital data" [2]. Popular points, using graphic coding is the basic method of organizing and using graphic data (including non-geody attribute data). The so-called graphics coding method is based on graphic symbols, in accordance with industry design specifications, drawing or labeling icons, the whole process of attributes, is a graphics coding method. In short, the drawing is encoded. Graphic encoding has existed before the computer graphics processing technology, the whole process of manual drawing, is the graphics encoding method, but the scope is limited to the narrow graphic symbol. With the rapid development of computer technology, the scope of use of graphics coding has long been exceeding narrow drawing design. Sikikikikikiki is a specific application of typical graphics encoding in the table database. The DOS operating system is the most essential difference between the Windows operating system. The former uses the digital encoding command system. The latter uses a graphic coding command system. Unfortunately, since the essence of non-geocotent data is graphical data, it is not recognized that the drawing annotation process is the encoding process, or the relational database technology is too popular, and the programming staff of the GIS related industry will be non-geographical properties. Data Division, centrally stored in a built-in or plug-in relational database, and people add a coded field to perform daily query statistics. This is not established, simple graphics symbols, such as barcodes, such as striking graphics symbols, such as stroke, and a string of digital symbols and its logic relationships, it is not possible to use digital code, otherwise there is no existence Engineering Design Languages in Industry. In the actual application, the query statistical effect in the relational database is in the relational database, and the operator is always in the fog. More troubled is that managers have exhausted the company's external coding system, but they have always collected. The coded dictionary of non-geodatabase is the industry design specification well known. The programming staff must first master the engineering design specification for GIS and related industries, and then the organization and design of the application system can be performed. Non-geocotential data uses a graphic encoding method to meet the principles of data modular design. The basic data module of the GIS-related industry is the geographic arrangement of each professional icon (attribute), which is a basic data module that can be used independently based on different types of icon entities, accurately connected according to their respective industry specifications. . This cannot be implemented in the relational table database, the table database is a slibecetable method, and different types of attribute data cannot be integrated in the same table book. This is both its advantages and is also inadequate. Data processing technology is not only a relationship type database. The programmer first considers the data processing technology according to different industry data characteristics.
