Rational drawing method of corners of map vector line elements based on gpu

A vector line and rationality technology, which is applied in the field of GPU-based map vector line element corner rationality drawing, can solve problems such as unreasonable drawing of vector line elements, achieve enhanced drawing effect and readability, and avoid redrawing and missing drawing Effect

CN105701759BActive Publication Date: 2018-08-10NANJING NORMAL UNIVERSITY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2018-08-10

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Abstract

The present invention relates to a symbolic rendering technology of the GIS field and the digital map making field, and provides a map vector line element corner reasonability drafting method based on a GPU which realizes the linear vector element reasonable drawing based the method. The method comprises the following steps of firstly generating a corresponding color structural table according to a map symbol unit needing to be filled, and making a special column as a background column in the color structural table; then constructing a line triangulation network after triangularization according to line widths, transmitting a U parameter along a line direction and a V parameter vertical with the line direction to each vertex in the triangulation network, adjusting the U values when the vertexes are valuated with the U values and if the filling at the corners is the background column; and finally transmitting the color structural table and the U-V parameters to a shader program, and carrying out the per pixel drawing on the line elements based on the color structural table by utilizing the Shader language and according to the U-V value of each vertex.
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Description

technical field

[0001] The invention relates to a symbolic rendering technology in the fields of GIS and electronic map, and provides a method for drawing rationality of corners of map line elements based on GPU (Graphics Processing Unit) programmable pipeline and Shader language. Background technique

[0002] The symbolization method of geospatial entities is an important research content in the field of geographic information and cartography. Compared with commonly used point symbols and surface symbols, line symbols are often more difficult and time-consuming because they need to be filled and drawn along the direction of linear elements. In addition to the commonly used solid lines and dashed lines, the line symbols required in map representations are more complex. For example, the linear symbol of a major urban road is a double-line graphic entity with a border; the railway symbol is a black and white graphic entity with a border; the single-sided boundary line symbol ...

Examples

Embodiment

[0032] Compared with the straight line drawing in the traditional computer visualization field, due to the complexity of map symbols, the drawing of map vector line features is more difficult. The traditional method, which uses different interval parameters to adjust the drawing errors at the corners, is difficult to meet the requirements of map drawing, and also causes the loss of spatial information transmission. Therefore, the present invention designs a GPUShader-based map line element corner rationality drawing method to adapt to the correct drawing of different map symbols. Such as Figure 6 As shown, the method of the present invention is used to draw four typical corners, as well as the wrong results drawn by other methods for the same vector line element.

[0033] The following is a software method, in the C++ language and OpenGL environment, to realize the rationality drawing method of the corners of map line elements based on GPU Shader:

[0034] (1) Define the st...