The concept of GIS?

Basic concept set of geographic information system

1, Geographic Information System (GIS), a new discipline integrating computer science, informatics, geography and other sciences, is a spatial information system supported by computer software and hardware, which uses the theories of system engineering and information science to scientifically manage and comprehensively analyze geographic data with spatial connotation, so as to provide needed information for planning, management, decision-making and research. GIS has the following subsystems: data input subsystem, data storage and retrieval subsystem, data operation and analysis subsystem and report subsystem.

information system

Nonspace space

Management information system non-geographic GIS

List of other geographic information systems of CAD/CAM

Social economy and population census are based on non-land and land.

2. Compare the similarities and differences among GIS, CAD and CAC.

CAD-Computer Aided Design, a system for generating, editing and displaying regular graphics, has nothing to do with external description data.

CAC- Computer Aided Cartography is a special software suitable for cartography, but it lacks the ability of spatial analysis.

GIS is a kind of geographic information system, which integrates conventional graphics and map drawing, and has strong spatial analysis ability.

3. Layer: Divide the special topics of spatial information according to its geometric characteristics and attributes.

4. Geographic data collection-field investigation and sampling; Traditional measurement methods, such as triangulation and trilateration; Global positioning system; Modern remote sensing technology; Biological telemetry; Digital photography technology; Census.

5. Information Paradigm-The traditional mapping method is called information paradigm, which assumes that the map itself is a final product, and it is a mode of exchanging spatial information by using symbols and selecting classification restrictions. This example is a traditional perspective method. Because of its primitiveness and many restrictions, it is not easy for map users to obtain pre-classified data. In other words, users are limited to the final product, and cannot reorganize the data into a more effective form to adapt to changes in the environment or requirements.

6. Analysis example (overall example)-Store the attribute data of the original data, and display, reorganize and classify the data according to the needs of users. Holistic paradigm is a real holistic method used in cartography and geography.

7. Grid-Grid structure is the simplest and most direct spatial data structure, which refers to dividing the earth's surface into grid arrays with uniform sizes and close to each other. Each grid is defined as a pixel by rows and columns, and contains a code indicating the attribute type or size of the pixel, or just a pointer to its attribute record. Therefore, the grid structure is a data organization that represents the distribution of spatial features or phenomena in a regular array, and each data in the organization represents the non-geometric attributes of features or phenomena. Features: the attribute is explicit and the positioning is implicit, that is, the data directly records the attribute itself, and the position is converted into corresponding coordinates according to the row and column number, that is, the positioning is obtained according to the position of the data in the data set. In the grid structure, points are represented by a grid unit; Linear objects are represented by a group of adjacent grid cells along a straight line, and each grid cell has at most two adjacent cells on the straight line; A face or region is represented by a group of adjacent grid cells with region attributes, and each grid cell can have more than two adjacent cells belonging to the same region.

8. Vector-It assumes that the geographical space is continuous, and points, lines, polygons and other geographical entities are represented as accurately as possible by recording coordinates. The coordinate space is set to be continuous, allowing precise definition of any position, length and area. For point entities, only their coordinates and attribute codes in a specific coordinate system are recorded in the vector structure; For linear entities, it is represented by a series of coordinate pairs; Polygon refers to a space area with completely closed boundaries, which is represented by a series of coordinate pairs.

9. The word "topology" comes from Greek, and its original meaning is "the study of shapes". Topology is a branch of geometry, which studies the geometric properties that can remain unchanged under topological transformation-topological properties (topological properties: one point is at the end of arc segment and one point is at the boundary of region; Non-topological attributes: distance between two points, length of arc segment, perimeter and area of area). This structure should include: unique identifier, polygon identifier, outer polygon pointer, adjacent polygon pointer, boundary link and range (maximum and minimum X and Y coordinate values). Connectivity of three important topological concepts (1) in geospatial research: the interconnection of arc segments at nodes; (2) Definition of polygon region: A plurality of arc segments are connected end to end to form the inner region of polygon; (3) Adjacency: By defining the left and right sides of the arc segment and their directionality, the adjacency of the left and right polygons of the arc segment can be judged.

10. Entity error of vector pseudo-node: that is, the node that the pseudo-node needs to identify occurs where a straight line connects with itself (such as an island pseudo-node, indicating that there is an island polygon inside another larger polygon), or where two straight lines intersect along parallel paths instead of crossing paths (node-a special point indicating the connection between straight lines). Swing node: sometimes called swing, it comes from three possible error types: polygon failed to close; Head-down line, that is, the node is not extended enough to connect with the target that should be connected; The line of the node exceeds the entity to be connected. Polygon fragmentation: It is caused by poor digitization process along the same boundary line. At the boundary line, the line must be digitized several times. Highly irregular national borders, such as Central America, are particularly prone to this kind of digital distortion. Label error: Missing and duplicate labels. Abnormal polygon: a polygon with missing nodes. The lost arc.

1 1, spatial analysis method-1, spatial information measurement: line and polygon measurement, distance measurement, shape measurement; 2. Spatial information classification: range classification, neighborhood function, roaming window and buffer; 3. Overlay analysis: polygon overlay, point and polygon, line and polygon; 4. Network analysis: path analysis, address matching and resource matching; 5. Spatial statistical analysis: interpolation, trend analysis and structure analysis; 6. Surface analysis: slope analysis, aspect analysis, visibility and mutual visibility analysis.

12, Euler number-the most common spatial integrity, that is, the measurement of the number of cavities in the cavity area. The measurement method is called Euler function, which only uses a single number to describe these functions, called Euler number. Numerically, Euler number = (number of holes)-(number of fragments-1), where the number of holes is the number of polygon holes contained in the outer polygon itself and the number of fragments is the number of polygons in the fragment area. Sometimes the Euler number is uncertain.

13, functional distance-describes the functional relationship between two points, such as time, friction, consumption, etc. These methods of measuring distance are collectively called functional distance.

14, Manhattan distance-the distance between two points in the north-south direction plus the distance in the east-west direction, that is, D(I, J)= | Xi-XJ |+| i -YJ|. For a town street with regular layout, due south, due north, due east and due west, the distance from one point to another is just the distance from north to south plus the distance from east to west, so Manhattan distance is also called taxi distance. Manhattan distance is not a distance invariant, and the distance between points will be different when the coordinate axis changes.

15. Neighborhood function-Neighborhood refers to a solid area with unified attributes or a small part of the solid space with the center of gravity in the whole area. Neighborhood function is to find the consistency of its attributes in a specific entity space. It includes direct neighborhood and extended neighborhood.

16, buffer analysis-refers to the spatial analysis method that automatically establishes the polygon entities of the buffer within a certain width range around the database according to the entity basis of points, lines and surfaces, so as to realize the horizontal expansion of spatial data. To some extent, the buffer zone is controlled by the existing friction surface, terrain, obstacles and so on. That is to say, although the buffer is based on location, there are other substantive components. There are four basic methods to determine the buffer distance: random buffer, cause buffer, measurable buffer and legal authorization buffer.

17. Statistical surface-surface is a shape with z value, also called height value, whose position is defined by a series of x and y coordinate pairs and distributed in the region. The z value is also often considered as the elevation value, but it is not necessarily limited to this measurement. In fact, any measurable value (such as ordinal number, interval and ratio data) that appears in a definable area can be considered as a surface. The commonly used term is statistical surface, because the z value constitutes the statistical expression of many elements in the consideration range (Robinson et al., 1995).

18, DEM- digital elevation model. Terrain model contains not only elevation attributes, but also other surface morphology attributes, such as slope and aspect. DEM is usually represented by an elevation matrix composed of regular grid elements on the surface, and the generalized DEM also includes all digital representations representing the surface elevation, such as contour lines and triangulation. In geographic information system, DEM is the basic data for establishing digital terrain model, and other terrain elements can be directly or indirectly derived from DEM, which is called "derived data", such as slope and aspect.

19, spatial interpolation-spatial interpolation is often used to convert the measured data of discrete points into continuous data planes for comparison with the distribution patterns of other spatial phenomena. It includes two algorithms: spatial interpolation and extrapolation. Spatial interpolation algorithm: calculate the unknown point data in the same area through the data of known points. Spatial extrapolation algorithm: Deduce the data of other regions through the data of known regions. 20. Tai Sen Polygon-A method of mathematically defining and bisecting the space between points and connecting them with straight lines to generate polygons between point objects.

2 1, linear density-the total line length of all regions divided by the area of the region.

22. Connectivity-Connectivity is a measure of network complexity, which is often calculated by γ index and α index. Wherein, the gamma index is equal to the ratio of the number of connection lines of a given spatial network body node to all possible connection lines; The α index is used to measure loops, and the degree to which nodes are connected by backup paths is called the α index, which is equal to the ratio of the number of existing loops to the number of maximum possible loops.

23. Graphic Overlay-Place the theme information represented by the graphics of one selected theme on top of the theme information represented by the graphics of another selected theme.

24. Automatic grid superposition-Polygon superposition based on grid cells is a simple process, because the area is an irregular block composed of grid cells, and * * * enjoys the same set of values and related labels. There is no doubt that polygon overlay based on grid cells lacks spatial accuracy, because the grid cells are larger, but similar to the same part of simple point-polygon overlay and line-polygon overlay, it can obtain higher flexibility and processing speed because of its simplicity.

25. Topological vector superposition-how to determine the functional relationship between entities, such as defining left and right polygons connected by special lines, defining the relationship between line segments to check traffic flow, or searching for selected entities according to a single entity or related attributes. It also establishes a method of overlapping multiple polygon layers to ensure that the attributes connecting each entity can be considered, thus supporting composite polygons that combine multiple attributes. The result of this topology is called the least common geographical unit (LCGU).

26. Vector Polygon Overlay-The main problem of point and polygon overlay and line and polygon overlay is that lines don't always appear in the whole area. The most powerful way to solve this problem is to let the software determine the intersection point of each group of lines, which is the so-called node. The task of superimposing vector polygons is basically the same. In addition to calculating overlapping intersection points, you must also define the attributes of polygon lines related to them.

27. Boolean superposition-superposition operation based on Boolean algebra.

28, drawing modeling-used to represent the application of command combination to answer questions about spatial phenomena. Cartographic model is a series of interactive and orderly map operations on original data (including derived data and intermediate map data simulating spatial decision-making).

29. Types of geographical models-descriptive models similar to statistics and conventional models related to inferential statistical techniques.

30. Common models-1. Focusing on style and handling problems has long been used to explain the relationship between agricultural activities and transportation costs-independent state model. 2. Weber model was originally designed to predict the spatial distribution pattern of industrial location, which can be improved to enable participants to find the best location-location-distribution model for business and service. 3. Gravity model is an economic geography model, which is based on the inverse ratio between attraction and the distance to the potential market. 4. The idea of spatial verification is now widely used in ecological communities, tracking the movement of animals and plants through geographical space-improving the diffusion model.

3 1, thematic map-a map whose main purpose is to show the location of a single attribute or the relationship between several selected attributes. The general program of theme graphic design includes selecting, generating and placing appropriate symbols and graphic objects, so as to clearly highlight the important attributes and spatial relations of the research theme, and at the same time consider the reference system. The rules of GIS thematic map output: not only must there be exquisite graphics, but the most important thing is to understand and analyze the map.

32. Metadata-Data about data, a comprehensive description of the contents of the database, the purpose of which is to promote the efficient use and full enjoyment of the data set. Reasons for using metadata: performance, integrity, expansibility, particularity and security; Functionally, error function, browsing function, program generation.

33. Aggregation-A large number of digital processing processes that classify individual data elements.

34. Kriging method-an accurate interpolation method for determining elevation based on the probability that the natural surface of the earth changes with distance.

35. Quadtree, a compressed data structure, quantificationally divides the geographical space into grids with different sizes, and each grid has the same attributes.

36. Compare the similarities and differences between instrumental GIS and applied GIS.

Tool-based geographic information system is a general geographic information system with general functions and characteristics, which provides users with a unified operating platform. Generally, there is no geospatial entity, but it is defined by users themselves. It has good secondary development function. Such as ArcInfo, Genamap, MapInfo, MapGIS, GeoStar.

Applied geographic information system: a geographic information system designed to solve one or more practical problems based on mature tool GIS software and according to users' needs and application purposes. It has geospatial entities and models to solve the special geospatial distribution. Such as Lisi, CGIS, UGIS.

37. Describe the development process of applied geographic information system in detail.

1. Overall system design: demand and feasibility analysis, data model design, database design and method design.

2. System software design: development language, user interface, process and interaction.

3. Programming: projection, database, input and editing.

4. System debugging and operation: α debugging and β debugging.

5. Evaluation and maintenance of the system: function evaluation, cost evaluation and benefit evaluation.

38. Spatial information system: based on multimedia technology and virtual reality, it integrates the input, editing, storage, analysis and display of spatial data. It consists of several subsystems.

39, geographic data measurement standards-naming (named data allows us to declare what we call an object, but we can't directly compare two named objects), ordinal number (providing logical comparison results of spatial objects, but this comparison is limited to the scope of the problem under discussion), interval (you can assign values to the items to be measured one by one, so that you can estimate the difference of comparison more accurately), ratio (the most widely used measurement data standard).

40. Sampling principle based on sample reasoning-data at non-sampling locations can be inferred from data at sampling locations; The data within the regional boundary can be combined and calculated; The data in one set of spatial units can be converted into another set of spatial unit data with different spatial configurations. Commonly used methods: interpolation method: when there is a numerical boundary or the values at both ends of the missing part are known; Extrapolation: When one side of the missing data has a value, the other side has every value.