CN101281699A - Geographic feature instance symbolization method - Google Patents

Abstract

The invention relates to a method for symbolizing geographical element instances: defining a map symbol template, which is composed of basic graphic element types and configuration parameters, establishing a mapping model from a map symbol template to a map symbol instance, and the mapping relationship of the mapping model is determined by the mapping method and Corresponding mapping parameter expression; analyze all geographic feature instances of the geographic feature class, determine the corresponding mapping parameter value according to the characteristics of each geographic feature instance and its relationship with other geographic feature instances; map the map symbol template according to the mapping parameter value A map symbol instance adapted to the characteristics and relationship expressions of geographic feature instances; symbolize geographic feature instances according to map symbol instances. The present invention realizes the symbolization method at the instance level of adaptive geographic elements, upgrades the current stage of symbolic expression expressing the characteristics of geographical elements to the stage of map expression expressing the characteristics and relationships of individual instances of geographic elements, and realizes the in-depth analysis of geographic information. Hierarchical visualization.

Description

Geographic feature instance symbolization method

technical field

The invention belongs to the technical field of geographic information, in particular to a method for symbolizing geographic element instances.

Background technique

In geographic information system (GIS), visualization is an important part of geographic information technology, the main functional module of geographic information system, and the window for users to interact with geographic information. As a major form of geographic information visualization, maps have a history of thousands of years. Modern maps have strict mathematical foundations, systematic map symbol expressions, and comprehensive overviews. Maps are a scientific means of visual expression of geographic information. Therefore, the map expression function of geographic information has become one of the necessary functions of geographic information system. The existing geographic information system software and map drawing software mainly complete the symbolic expression of geographic information through the map symbol library module. Firstly, a set of map symbol library is established, which associates geographic feature classes with corresponding map symbols. When realizing the symbolization of geographic information, find the corresponding symbols according to the comparison table between elements and symbols, and use the drawing function of the symbol library to map geographical information. The elements are expressed symbolically. After the symbolization of all geographical elements is completed, the map expression of geographic information is realized. The results can be displayed on the display device or output as a paper map. However, this geographical information symbolization method based on the map symbol library only distinguishes the categories of geographical information, without further distinguishing the differences between individual instances of different elements in the same geographical information, for example: using blue solid lines of the same width to Drawing perennial rivers cannot visualize the differences in length and level of different rivers, which reduces the accuracy of geographic information transmission. In addition, the current geographic information symbolization method is limited to the symbolization of a single geographic element, ignoring the reasonable expression of the spatial relationship and attribute relationship between geographic information. For example, when drawing the intersection relationship of dashed roads, the existing GIS visualization will use The same dotted line schematic symbol is used to symbolize all the roads, so that the imaginary part intersects, which reduces the accuracy of the visual expression of the intersection and affects the reader's interpretation of the intersection. Therefore, in view of the shortcomings of the existing symbolic methods in GIS visualization, it is an urgent problem to transform GIS visualization from simply symbolizing geographical elements to map expression that takes into account the characteristics of individual instances of geographical elements and their interrelationships.

Contents of the invention

The purpose of the present invention is to provide a geographical element instance-level symbolization method with self-adaptive characteristics, which can automatically calculate the mapping parameter value, and map the map symbol template into a map symbol instance that meets the needs of geographical element instance characteristics and interrelationship expression , so as to achieve a map expression that is more refined than the existing GIS visualization and can reflect the detailed characteristics and relationships of geographical element instances.

Technical scheme of the present invention comprises the following steps:

Step 1. Define map symbol templates. Map symbol templates are composed of basic primitive types and their configuration parameters. A mapping model from map symbol templates to map symbol instances is established. The mapping relationship of the mapping model is expressed by the mapping method and corresponding mapping parameters;

Step 2, analyze all geographic feature instances of the geographic feature class, and determine its corresponding mapping parameter value according to the characteristics of each geographic feature instance and its relationship with other geographic feature instances;

Step 3, according to the mapping parameter values calculated in step 2, the map symbol template is mapped to a map symbol instance that adapts to the characteristics of the geographical feature instance and the expression of the relationship.

Step 4: Symbolize geographic feature instances according to map symbol instances.

Moreover, basic primitive types include ellipse, arc, sector, triangle, rectangle, polyline, and polygon, and configuration parameters include repeat configuration, fixed-point configuration, whether it can be deformed and whether it can be stretched.

Moreover, the mapping manner includes translation transformation, scaling transformation, rotation transformation, miscut transformation, phase transformation and polyline width gradient transformation.

And, in step 2,

For a point-like geographical feature instance with direction, determine the direction of the feature instance, and set the rotation transformation parameter value of the corresponding map symbol template according to the direction;

For the perennial river element class in the water system element, determine the length, grade, and upstream, downstream, and main tributary relationship of the element instance of this type, and set the polyline width gradient transformation parameter value of the corresponding map symbol template according to these attribute values;

For geographical feature instances represented by dotted line symbols, set the phase transformation parameter value of the corresponding map symbol template according to the value of the remainder of the length of the geographical feature instance and the length of the repeated basic primitive of the dotted line symbol.

And, in step 3,

For a point-like geographical feature instance with direction, the map symbol template is rotated and transformed according to the value of the rotation transformation parameter to obtain a map symbol instance expressing the corresponding directed point symbol;

For the perennial river feature class in the water system elements, the map symbol template is subjected to width scaling transformation according to the polyline width gradient transformation parameter value, and the map symbol instance expressing the corresponding gradient linear symbol is obtained;

For the instance of geographic elements represented by dotted line symbols, the phase change of the repeated basic primitives expressing dotted line symbols in the map symbol template is carried out according to the phase transformation parameter value, so that the repeated basic primitives configured along the central line are real at the first and last points. department drawing.

The present invention innovatively proposes to distinguish the schematic symbols representing the common features of terrain elements from the instance symbols representing the characteristics and relationships of individual instances of elements in the cartography process, and establish a mapping relationship between map symbol templates and map symbol instances, according to The specific characteristics of the geographic feature instance and their interrelationships automatically calculate the corresponding mapping parameters, so that the map symbol template mapping is converted into a map symbol instance that is suitable for the instance, and the map symbol instance is used to finely express the characteristics of the current geographic feature instance and relationships, and finally realized the instance-level symbolization of adaptive geographic features. The method provided by the present invention raises the focus of symbolization from the layer level of geographical elements to the level of individual instances of geographical elements, fully considers the deep-level visualization of GIS at a more detailed level, that is, the demand for map expression, and improves the GIS The quality of visualization enhances the efficiency of geographic information transmission. The technical scheme of the invention is easy to implement, has excellent flexibility and versatility, and can enhance the map visualization function in the geographic information system and the map drawing system.

Description of drawings

Fig. 1 schematic diagram of the mapping model principle of the embodiment of the present invention;

Fig. 2 is a schematic diagram of rotation transformation of an embodiment of the present invention;

Fig. 3 is a schematic diagram of gradient transformation according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of phase transformation according to an embodiment of the present invention;

Fig. 5 draws the entrance and exit of the self-adaptive undercurrent river according to the embodiment of the present invention;

Figure 6 is the drawing result of the self-adaptive water system element of the embodiment of the present invention;

Fig. 7 is the drawing result of the self-adaptive traffic element of the embodiment of the present invention;

Detailed ways

The present invention aims at the deficiencies in the cartographic expression of geographic information in the existing GIS visualization, uses traditional map drawing knowledge to guide the GIS visualization, and provides a technical solution comprising the following steps:

Step 1. Define map symbol templates. Map symbol templates are composed of basic primitive types and their configuration parameters. A mapping model from map symbol templates to map symbol instances is established. The mapping relationship of the mapping model is expressed by the mapping method and corresponding mapping parameters;

The definition of the map symbol template in the present invention is formed on the basis of statistical analysis of the existing national basic scale map schema symbol system, and is described in the form of graph elements. According to the results of the analysis of the schematic symbols, the map symbol template of the embodiment of the present invention defines seven basic primitive types: ellipse, arc, sector, triangle, rectangle, polyline, polygon, and four configuration parameters: repeated configuration, Fixed-point configuration, whether it can be deformed, whether it can be stretched. This set of basic primitive types can basically meet the drawing needs of drawing map symbol templates through the combination of primitive types and configuration parameters. During specific implementation, more basic primitive types and configuration parameters can be defined as required, but they are all within the scope of protection claimed by the present invention. On the basis of summarizing the knowledge of traditional map drawing, the present invention proposes to establish a set of mapping models from map symbol templates to map symbol instances, which can express the characteristics and interrelationships of individual instances of geographic elements. The model can not only describe the properties of the schematic symbols that reflect the overall characteristics of the geographical feature class, but also define the mapping transformation parameters, so as to support the mapping transformation from the schematic symbols to the symbol instances that reflect the characteristics of individual instances of geographic features.

The focus of the present invention is to reflect the characteristics and interrelationships of individual instances of geographic elements in the process of GIS visualization. Therefore, on the basis of the description of the basic map symbol template, the present invention proposes to obtain a map symbol instance adapted to the expression of the geographical element instance through mapping conversion according to the characteristics of the geographical element instance. The specific mapping methods provided by the embodiments of the present invention may include translation transformation, scaling transformation, rotation transformation, miscut transformation, phase transformation, and polyline width gradient transformation. The corresponding mapping parameters are translation transformation parameters, scaling transformation parameters, rotation transformation parameters, miscut transformation parameters, phase transformation parameters and polyline width gradient transformation parameters. The first four transformations output conventional affine transformations; the phase transformation is to periodically transform the initial drawing position of the repeated configuration unit of the map symbol on the unit; the polyline width gradient transformation determines the initial width and End width. During specific implementation, the types and numbers of the prescribed mapping methods can be selected according to needs, so as to realize more precise changes.

Step 2, analyze all geographic feature instances of the geographic feature class, and determine the corresponding mapping parameter values according to the characteristics of each geographic feature instance;

Referring to the embodiment of the present invention in Fig. 1, the principle of symbolization by the mapping model is: 1 geographic feature class includes N geographic feature instances [1:N], according to the feature instance attributes (i.e. features and interrelationships) of the geographic feature instances ) to extract the mapping method and parameters, the map symbol template is transformed into a map symbol instance [1:N] through the mapping transformation parameters, and then the map symbol instance is used to symbolize the corresponding geographic element instance [1:1] to realize the visualization of deep geographic information.

In order to facilitate implementation, the present invention provides further specific technical solutions for several outstanding difficulties in the existing visualization technology:

For a point-like geographical feature instance with direction (such as a cave dwelling), the result of symbolization should be a directed point symbol, so it is necessary to determine the direction attribute of the feature instance, and obtain the rotation transformation parameter value of the corresponding map symbol template according to the direction.

For the perennial river element class in the water system element, the ideal result of symbolization is to express the difference in length and level of different rivers visually. Therefore, it is necessary to determine the length, level, and upstream and downstream, main tributary relationship. By setting the polyline width gradient transformation parameters of the map symbol template according to these attribute values of the feature instance, the starting drawing width and ending drawing width of the corresponding map symbol instance can be determined.

For geographical feature instances represented by dotted-line symbols, the ideal result of symbolization is to draw the real part at the intersection of the symbols, so that map readers can clearly identify the position of the intersection point and the direction of the dotted-line symbol. Therefore, according to the value of the remainder of the length of the geographical element instance and the length of the repeated basic primitive of the dotted line symbol, the phase transformation parameters of the map symbol template corresponding to the element instance are set. The repeated basic primitives expressing dashed line symbols are generally polylines with a small length.

Step 3, according to the mapping parameter values calculated in step 2, the map symbol template is mapped to a map symbol instance that adapts to the characteristics of the geographical feature instance and the expression of the relationship.

In this step, based on the mapping model established in step 1, only the mapping parameter values obtained in step 2 need to be brought in to obtain a definite mapping relationship and a map symbol instance that adapts to the characteristics of geographical element instances and the relationship expression. The specific implementation corresponds to step 2:

For a point-like geographical element instance with direction (such as a cave dwelling), the map symbol template is rotated and transformed according to the value of the rotation transformation parameter to obtain a map symbol instance expressing the corresponding directional point symbol.

For the perennial river feature class in the water system elements, the map symbol template is scaled and transformed according to the polyline width gradient transformation parameter value, and the map symbol instance expressing the corresponding gradient linear symbol is obtained. In essence, the start width and end width of the gradient line symbol are obtained by changing the parameter value of the polyline width gradient.

For the instance of geographic elements represented by dotted line symbols, the phase change of the repeated basic primitives expressing dotted line symbols in the map symbol template is carried out according to the phase transformation parameter value, so that the repeated basic primitives configured along the central line are real at the first and last points. department drawing.

Step 4: Symbolize geographic feature instances according to map symbol instances.

The geographic element instance symbolization method provided by the present invention can be combined with the existing geographic information system software, and a computer can be used to realize the adaptive geographic element instance-level symbolization. During specific implementation, it can be realized through the following steps through software settings:

(1) A map symbol library module is set in the computer system, and a map symbol template is established in the map symbol library. The map symbol template is composed of basic primitive types and configuration parameters.

Then, establish the corresponding relationship between the map symbol template and the geographic feature class in the form of a comparison table in the computer, and store the codes of the geographic feature class and the map symbol template in a one-to-one correspondence in the database. This provides the basis for the mapping model.

(2) In the computer system, traverse all the individual instances of geographic elements in each layer in turn, and determine the mapping transformation parameter value of the map symbol template according to the attributes of the instance, for example, according to the direction of the directional point or the direction line attribute to determine the rotation transformation parameter value of the map symbol template; determine the polyline width gradient transformation parameters (polyline start width and end width) of the map symbol template according to the length and level of the water element instance; according to the road element instance represented by a dotted line The ratio of the length to the repeated primitives in the dotted symbol determines the phase transformation parameter value of the map symbol template.

(3) Apply these mapping transformation parameters to the map symbol template in the computer system, so as to obtain the map symbol instance that can adapt to the expression of the current geographical element instance. The specific performance may be to adjust the geometric parameters and configuration parameters of the basic primitives in the map symbol template according to the mapping change parameters. Examples of specific operations: transform the coordinate values of the primitives (points or polylines) expressing directed point symbols to obtain the primitive coordinates of map symbol instances (see Figure 2); convert the primitives (polylines) expressing symbols of water system The endpoint width is set to the start width and end width obtained by the gradient transformation of the polyline width (see Figure 3); the repeated basic primitives expressing the symbols of the traffic elements (the polylines with a relatively long length used to form the dotted line symbol) are carried out according to the phase transformation parameters Periodic movement (see Figure 4). Arrows in Figures 2 to 4 indicate transitions.

(5) Use the symbolization function in the map symbol library system to symbolize and draw the current geographic element instance according to the symbol instance.

Because in the current geographic information system software, the visualization function is only a simple symbolization, it is difficult to show the characteristics of the individual instances of geographic elements and their relationship, which reduces the quality and effect of information transmission of geographic information visualization. Therefore, after the present invention establishes the mapping model of map symbols, it fully considers the characteristics of individual instances of geographical elements, and can calculate symbol instances that can express the characteristics of such instances through the mapping model, thereby enhancing the visualization function of geographic information and fully reflecting The overall structural character of geographic information in a cartographic area.

Referring to Figures 5 to 7, in order to facilitate the visual understanding of the symbolic effect of the instance-level adaptive elements provided by the present invention, the present invention provides instance-level examples of the self-adaptive geographical elements of the entrance and exit of the underground river, the perennial single-line river, and the dotted road in the embodiment. Symbolize the result. It can be clearly seen that the results of these computer adaptive renderings have fully completed the task of map expression of corresponding geographic information, which meets the needs of digitalization in the field of geographic information.

Claims (5)

1. A geographical element instance symbolization method is characterized in that comprising the following steps: Step 1. Define map symbol templates. Map symbol templates are composed of basic primitive types and their configuration parameters. A mapping model from map symbol templates to map symbol instances is established. The mapping relationship of the mapping model is expressed by the mapping method and corresponding mapping parameters; Step 2, analyze all geographic feature instances of the geographic feature class, and determine its corresponding mapping parameter value according to the characteristics of each geographic feature instance and its relationship with other geographic feature instances; Step 3, according to the mapping parameter values calculated in step 2, the map symbol template is mapped to a map symbol instance that adapts to the characteristics of the geographical feature instance and the expression of the relationship. Step 4: Symbolize geographic feature instances according to map symbol instances. 2. The method for symbolizing geographical element instances according to claim 1, characterized in that: the basic primitive types include ellipses, arcs, sectors, triangles, rectangles, polylines and polygons, and the configuration parameters include repeated configurations, fixed-point configurations, possible deformation and elongation. 3. The method for symbolizing geographic element instances according to claim 1 or 2, wherein the mapping methods include translation transformation, scaling transformation, rotation transformation, miscut transformation, phase transformation and polyline width gradient transformation. 4. The geographical element instance symbolization method according to claim 3, characterized in that: in step 2, for the point-shaped geographic element instance with direction, determine the direction of the element instance, and set the corresponding map symbol template according to the direction The rotation transformation parameter value of ; For the perennial river element class in the water system element, determine the length, grade, and upstream, downstream, and main tributary relationship of the element instance of this type, and set the polyline width gradient transformation parameter value of the corresponding map symbol template according to these attribute values; For geographical feature instances represented by dotted line symbols, set the phase transformation parameter value of the corresponding map symbol template according to the value of the remainder of the length of the geographical feature instance and the length of the repeated basic primitive of the dotted line symbol. 5. The method for symbolizing geographic feature instances according to claim 4, characterized in that: in step 3, for point-like geographic feature instances with directions, the map symbol template is rotated and transformed according to the rotation transformation parameter value to obtain expression A map symbol instance corresponding to a directed point symbol; For the perennial river feature class in the water system elements, the map symbol template is subjected to width scaling transformation according to the polyline width gradient transformation parameter value, and the map symbol instance expressing the corresponding gradient linear symbol is obtained; For the instance of geographic elements represented by dotted line symbols, the phase change of the repeated basic primitives expressing dotted line symbols in the map symbol template is carried out according to the phase transformation parameter value, so that the repeated basic primitives configured along the central line are real at the first and last points. department drawing.

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