[Visitor (112.0.*.*)]answers [Chinese ]  Time :20220603  (1) Representation method of pointlike elements: fixedpoint symbol method
Pointlike features are often represented by fixedpoint symbolism, referred to as symbolic law. It is a symbol of various shapes, sizes, colors, and structures that represent the spatial distribution of thematic features and their quantitative and qualitative characteristics. Usually the position of the symbol represents the spatial distribution of thematic features, the shape and color indicate the difference in quality, the size indicates the difference in quantity, the structure symbol represents the internal composition, and the positioning extension symbol indicates the development dynamic.
(2) Representation method of linear elements: linear symbol method Linear or strip distribution features, usually using color and graphics to represent the quality characteristics of linear elements, such as using colors to distinguish different tourism routes, passenger flow routes in different periods, different river types, etc.; Use symbol weight to indicate hierarchical differences; The position of the symbol is usually depicted on the center line of the represented thing (such as the traffic line), and some are depicted on one side of the linear thing, forming a certain width of colored bands or halo bands (such as coastal types, realm line halos, etc.); The length of the symbol represents the number of thematic features, such as the length of the highway symbol. The linear symbol method is commonly used to compile water system maps, transportation maps, geological formation maps, tour guide maps, and road maps.
(3) The representation method of polygonal elements Polygon features can be summarized into three forms according to the spatial distribution characteristics: one is the features covered with cartographic areas, which can be represented by the mass bottom method, the contour line method and the positioning chart method; The second is the intermittent fragmentary distribution of elements, which can be expressed by the range method; The third is a discrete distribution feature, which is commonly expressed by the point value method, the hierarchical ratio method, the partition statistical chart method and the triangle chart method.
1. The quality bottom method, also known as the base color method, is to dye the color or fill in the halo and pattern within the regional boundaries or type range to show the quality differences of thematic elements covered with cartographic areas, and is often used in the preparation of various types of maps and zoning maps, such as landform type maps, agricultural zoning maps, climate type maps, etc 2. Contours are smooth curves formed by connecting the same numerical points of a thematic feature, such as contour lines, isothermal lines, isoprecipitation lines, isometric depth lines, etc. It is often used to represent thematic features that are continuously distributed on the ground and gradually change, and to indicate the numerical value and intensity of such features at any point on the map, and it is suitable for representing natural phenomena such as landforms, climate, and seashores. 3. The positioning chart method is to draw the statistical data of certain places in the form of charts on the corresponding locations of the map to indicate the changes of certain thematic elements in the place. The symbol height (length) or curve chart in commonly used column charts represents the change in the number of thematic features. Such as monthly or annual wind direction, wind changes, precipitation, temperature changes, etc., this method can be used. 4. The scope method ( ) is to use contour boundaries to represent the regional extent of the thematic features that are intermittently distributed in the cartographic area, and to represent the categories of things in the form of color, halo, annotation, symbols and other decoration methods; Represent quantities with numeric annotation. The range method is often used for the representation of thematic elements that are intermittently distributed in flaks (such as forests, resources, coal fields, oil, a crop, nature reserve, etc.).
5. The point value method (point number method) is a method of using points of a certain size and the same shape on the map to express the number, regional distribution and degree of density of thematic features. This method is used to express unevenly distributed thematic elements, such as population distribution, resource distribution, crop distribution, forest distribution, etc. 6. The hierarchical ratio method (hierarchical statistical chart method) is to divide the entire cartographic area into several small statistical areas according to administrative divisions (or natural divisions); Then divide the levels according to the concentration (density or intensity) or development level of thematic features in each statistical area, and then fill in different shades of color or different shades of color or different thicknesses and different thicknesses and different halos according to the level to show the difference in the number of thematic features. At the same time, changes in color from light to dark (or from dark to light) or halo from sparse to dense (or from dense to sparse) can also show the trend of concentration or dispersion of features. 7. The zonal statistical chart method is to divide the entire cartographic area into several statistical areas (according to administrative division units or natural divisions), and in each statistical area, according to its corresponding statistical data, different forms of statistical graphics are designed to represent the sum of thematic elements and their dynamics in each statistical area. It can be used to compile resource maps, statistical charts, economic income charts, economic structure charts, etc.
(4) Other methods of expression
1. Moving feature representation method  moving line method The representation method of moving elements (such as cargo flow, passenger flow, air mass movement route, traffic flow, etc.) is often used. The moving line method is a method of using a variety of arrow symbols of different shapes, colors, lengths, and widths to indicate the direction, route, quantity, quality, internal composition, and development dynamics of the thematic elements
2. Internal structure notation  triangle chart method
The graph of the triangle chart method is a map similar to the bottom method, but it mainly reveals the internal structural characteristics of the phenomenon of things, the zoning range of this kind of graph is each administrative unit or statistical area, and the triangle chart appears as a legend form.
3. Other methods In addition, a variety of statistical charts such as bar charts, crosssectional charts, rose charts, tower charts, and triangle charts are often used on thematic maps as a supplement to the map. The above methods are often applied in conjunction with each other.
Thematic maps are widely used and play an important role in economic and national defense construction, scientific research, culture and education. The content of the thematic map is a high summary of the knowledge accumulated by longterm research in various disciplines, and it also provides a scientific basis for indepth research and guidance of production. 
