Screen-based three-dimensional linear symbol rendering method

Abstract

The invention discloses a screen-based three-dimensional linear symbol rendering method, which utilizes a shader language to realize high-efficiency high-quality rendering of linear map symbols in a three-dimensional map. The method includes the steps of establishing a mapping relation between vector line segments and a terrain unit, and encoding vector nodes and indexes, thereby forming node texture and index texture; in a fragment shader, searching and reestablishing vector line segments associated with a current fragment; performing grouping and ranking on vector line segment indexes, solving texture coordinates of line segment nodes in the node texture, and reading node attributes from the node texture; and selecting corresponding rendering functions according to symbol types of the associated line segments, and arranging a calculation sequence according to priority. Through direct calculation of screen fragments, the screen-based three-dimensional linear symbol rendering method provided by the invention can realize lamination rendering of linear symbols in a terrain rendering process. In addition, precise spatial position relation calculation and flexible fragment operation meet rendering of different types of linear symbols, and ensure efficiency of real-time rendering.

Description

technical field

[0001] The invention belongs to the fields of computer graphics and cartography, and in particular relates to a screen-based three-dimensional linear symbol rendering method. Background technique

[0002] The current research on the rendering of 3D linear symbols has the following three aspects:

[0003] (1) Texture-based method

[0004] The method based on texture mapping considers vector lines as part of the texture. According to this idea, the line symbols are rasterized and fused to the texture image. This process can be performed during preprocessing or real-time rendering. Mapping the texture with the symbol onto the terrain model allows for an exact match between the symbol and the terrain surface. Due to the limited resolution of raster imagery, the edges of vector symbols appear jagged when the scene is scaled. One solution is to generate textures in the GPU in real time, but this method is only effective for flat terrain; Zhi et al. proposed a vi...

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