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The concept of symbolization

Symbolization technology is to classify, simplify, exaggerate and other methods of spatial data to obtain the marks, according to their basic characteristics, relative importance and relevant positions to make various graphics.

Map symbol

Map symbol is the basic means to express the content of the map, it is composed of different shapes, sizes, colors and other graphics and words.

The efficacy of map symbols

  1. Selective represents an important feature, such as a stadium

  1. A plane symbol, such as a contour line, to indicate the undulation of the ground

  1. A feature of a geographical object, such as precipitation, that cannot be observed directly

  1. Natural and social phenomena, such as population distribution, that have no outward appearance

The characteristics of map symbols

  • Symbols are the means of spatial information transmission.

For example, we can know the characteristics and laws of population distribution in China through symbol description.

  • Symbolic model, not limited by the change of scale, can still reflect the basic appearance of the region.

For example, on a larger scale map, outline lines can be used to describe the city range, and on a smaller scale, point symbols can be used to express the spatial position of the city

  • Symbols provide great expressive power.

For example, landforms can be expressed by contour symbols, or by shading.

  • Symbols can construct conceptual models of phenomena that are difficult to express.

Such as the Spring Festival migration map.

Map symbol design requirements

  • Symbols should be associated with the specific features of the actual thing

  • There should be distinct differences between symbols

  • Things of the same kind should have similar symbols

  • Simple, beautiful and easy to remember

GIS visualization presentation method

Concept of GIS visualization

  • visualization

Is the use of computer graphics and image technology, the complex scientific phenomenon, natural landscape and some abstract concept of the process of graphics.

  • GIS visualization

Based on computer science, cartography, cognitive science and geographic information system, the method and technology of displaying spatial information in the form of screen map is intuitive, vivid, multi-dimensional and dynamic.

Classification of GIS visualization presentation methods

Positional notation

An object representing a point distribution, using a ratio symbol to express its quantitative relationship.

Linear notation

Used to represent linear objects (phenomena), such as rivers, traffic lines, etc.

Sports line method

Arrow symbols and stripes of different widths and colors indicate the direction, path, and quantitative and qualitative characteristics of phenomenon movement.

The scope of law

It refers to the plane object distributed in discontinuous slices, and its distribution range is represented by real or hidden contour lines, and its quality characteristics are distinguished by means of color, reticulation, symbols and even notes.

Qualitative method of bottom

Refers to the continuous distribution of planar phenomena, such as geological phenomena, land use, soil types, etc., throughout the region.

Isoline method

A planar phenomenon covering the whole region is represented by contour lines. It is most suitable for the expression of uniform and gradual natural phenomena such as topographic rise and fall, air temperature, precipitation and surface runoff all over the whole mapping area.

Points method

For the phenomenon of scattered and complex distribution in the mapping area, such as population and animal distribution, when the distribution range cannot be plotted, point groups of a certain size and shape can be used to reflect it.

Position chart method

A method for reflecting the quantitative characteristics and variations of periodic phenomena at some points located in the cartographic area in the form of graphs. For example, a monitoring station measures wind direction and speed chart

Hierarchical statistical graph method

According to the statistical data of each mapping unit (such as administrative division), the method of using different color levels or halos to reflect the concentration degree or development level of each division phenomenon.

  • Isometric grading: A method of dividing grades by the same difference.

  • Ratio grading: Grading by integral multiples.

In practical application, the rank spacing should be adjusted according to the data characteristics.

Divisional statistics chart issued

In each division unit, the statistical data are described into different forms of statistical charts and placed in the corresponding division unit to reflect the total amount, composition and change of phenomena in each division unit.

Map rendering function in GIS software

Select render fields and methods

Set parameters for different rendering methods

Set the symbol style

Show render effect