A method of disconnecting contour lines

Abstract

The invention relates to a contour line broken-line connection method, comprising obtaining a contour line broken-line single pixel thinned image, employing a GPU algorithm to recognize breakpoints and broken line connection. The contour line connection algorithm considers contour line mathematics attribute as well as contour line geographical attribute. The invention improves a local connection method based on minimum distance and direction difference least constraint, simultaneously considers the distance and direction among breakpoints in a matching breakpoint searching process, and sets more robust matching rules. The method has high accuracy, and can recover contour lines more accurately.

Description

technical field [0001] The invention belongs to the technical field of surveying and mapping geographic information extraction, and in particular relates to a method for connecting contour lines. Background technique [0002] A contour line is a closed curve formed by adjacent points of equal elevation on a topographic map. Generally speaking, the contour lines do not intersect each other. However, in the preprocessing of the color segmentation of the color topographic map, in the process of background removal and color segmentation, the contour lines will be broken due to color confusion and line elements overlapping. There are three specific reasons: [0003] First, the scanned color topographic map information is incomplete, and some contour line pixels are lost, which makes the topographic map before segmentation broken, which in turn affects the contour line segmentation effect. This break has great randomness. This leads to uneven distribution of pixel colors, makin...

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Problems solved by technology

This leads to uneven distribution of pixel colors, making some pixel colors on the contour line closer to the color of the regional features, and thus being mis-segmented into the background layer, resulting in contour line breaks, and the cracks may be larger

[0004] Second, color segmentation mainly uses the color information of pixels. When the contour line overlaps or intersects with other terrain identifiers, the color information of the contour line is overwritten, resulting in the contour line being divided into different layout layers. , such as the cover of the black square mesh will cause the contour line to break vertically or horizontally

This method has a higher accuracy rate, but the computational complexity is higher

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