Method for judging point whether or not situated in polygon

A polygon and judgment point technology, which is applied in image data processing, instruments, calculations, etc., can solve problems such as large space overhead, low judgment efficiency, and inconvenient polygon processing with a large number of sides.

Inactive Publication Date: 2008-01-30
INST OF SOFTWARE - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In practical applications, polygons with a large number of sides are often encountered, but the existing technical methods have a large space overhead, and it is not convenient to process polygons with a large number of sides, which is limited by space expression ability or computing power. , the judgment efficiency is not high

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  • Method for judging point whether or not situated in polygon
  • Method for judging point whether or not situated in polygon
  • Method for judging point whether or not situated in polygon

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Embodiment Construction

[0019] The method of the present invention mainly comprises following two phases: the first phase is to carry out convex dissection to given polygon, establishes balanced binary tree and manages convex polygon; Whether the detected point is inside the polygon.

[0020] 1. The implementation steps of the first stage are as follows:

[0021] First, divide the given polygon into some monotone polygons (that is, the sides of each such polygon can be divided into 2 monotone edge sequences) (see literature de Berg M, van Kreveld M, Overmars M, et al. Computational Geometry: Algorithms and Applications.2nd ed.Berlin: the method in Springer, 2000), and then each monotone polygon is convexly divided.

[0022] What the present invention adopted is a kind of convex subdivision method without adding points, and Fig. 1 is the convex subdivision operation figure of polygon, and its concrete steps are as follows:

[0023] 1) Divide the polygon into monotone polygons

[0024] a) Find all t...

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Abstract

The invention belongs to a method of judging whether a point is in a polygon, pertaining to a computer graphic and computer geometry technical field. The invention first convexly decomposes a polygon and builds a binary tree to manage these convex polygons; then the invention investigates the built binary tree according to the coordinate position of the tested point to find the convex polygon to which a leaf node of the binary tree corresponds; finally the invention tests whether the point is in the convex polygon or not, thus judging whether the tested point is in the given polygon or not. The invention has the advantages that the calculating speed is high and the storage space is saved compared with other similar methods based on polygon convex decomposition. The invention is applied to the condition that a plurality of points are judged whether in the same polygon.

Description

technical field [0001] The invention belongs to the technical fields of computer graphics technology and computational geometry, and in particular relates to a method for judging whether a point is located in a polygon. Background technique [0002] It is a basic problem in computational geometry to determine whether a point is located in a polygon, and the methods in this area are widely used in many fields such as computer graphics, pattern recognition, and geographic information systems. The methods in this respect can be divided into two categories, one is not to pre-process the polygon, and the other is to pre-process the polygon. [0003] In the former method, the most commonly used method is the ray method, that is, a ray is sent from the detected point, and the number of sides of the polygon intersected with it is calculated. If it is an odd number, the point is located in the polygon, otherwise it is located in the polygon. outside. This type of method needs to ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/60
Inventor 李静王文成
Owner INST OF SOFTWARE - CHINESE ACAD OF SCI
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