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  • 折线求等分点

    原理

    等分点标注法首先需要计算两个点之间的间隔,以便后续的计算。首先确定起始点为起始坐标,计算该点与下一个点之间的距离是不是大于或者等于间隔,如果是,计算x,y值,并且将起始点的坐标改变为计算所得的x,y值;如果距离小于间隔,则用间隔减去这两个点之间的距离,并且将起始点坐标改变为下一个坐标点的坐标。这样来进行逐条线段的处理,得到标注点的坐标。

    实现

    #! /usr/bin/env python
    # -*- coding: utf-8 -*-#
    # -------------------------------------------------------------------------------
    # Name:         折线求等分带
    # Author:       yunhgu
    # Date:         2021/10/27 11:46
    # Description: 
    # -------------------------------------------------------------------------------
    from math import sqrt, pow
    
    import cv2
    import numpy as np
    
    
    # 等分点标注法
    def polyline_get_dividing_points(points, num):
        dividing_points = []
        line_length = 0.0
        # 计算总长
        for index in range(len(points) - 1):
            x0, y0 = points[index][0], points[index][1]
            x1, y1 = points[index + 1][0], points[index + 1][1]
            line_length += sqrt(pow(x1 - x0, 2) + pow(y1 - y0, 2))
        # 计算每一段长度
        distance = line_length / num
        # 初始化当前长度
        cur_distance = distance
        # 起始点坐标
        x1, y1 = points[0][0], points[0][1]
        dividing_points.append([x1, y1])
        out_point = 0
        for index in range(1, len(points)):
            x2, y2 = points[index][0], points[index][1]
            while True:
                line_distance = sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2))
                if line_distance >= cur_distance:
                    x = (x2 - x1) * cur_distance / line_distance + x1
                    y = (y2 - y1) * cur_distance / line_distance + y1
                    out_point += 1
                    if out_point > num - 1:
                        break
                    dividing_points.append([x, y])
                    # 改变起始点坐标
                    x1 = x
                    y1 = y
                    cur_distance = distance
                # 当前线段长度不足时,考虑下一条线段
                else:
                    # 改变起始点的坐标
                    x1 = x2
                    y1 = y2
                    cur_distance -= line_distance  # 长度要减去之前线段的长度
                    break
        # 加入尾点坐标
        dividing_points.append([points[-1][0], points[-1][1]])
        return dividing_points
    
    
    # 等间隔标注法
    def polyline_equally_spaced_points(points, space):
        dividing_points = []
        line_length = 0.0
        # 计算总长
        for index in range(len(points) - 1):
            x0, y0 = points[index][0], points[index][1]
            x1, y1 = points[index + 1][0], points[index + 1][1]
            line_length += sqrt(pow(x1 - x0, 2) + pow(y1 - y0, 2))
        # 计算每一段长度
        division = line_length / space
        distance = 0
        if int(division) - division == 0:
            distance = space / 2.0
        else:
            distance = (line_length - int(line_length / space) * space) / 2.0
        # 起始点坐标
        x1, y1 = points[0][0], points[0][1]
        out_point = 0
        for index in range(1, len(points)):
            x2, y2 = points[index][0], points[index][1]
            while True:
                line_distance = sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2))
                if line_distance >= distance:
                    x = (x2 - x1) * distance / line_distance + x1
                    y = (y2 - y1) * distance / line_distance + y1
                    out_point += 1
                    dividing_points.append([x, y])
                    x1 = x
                    y1 = y
                    distance = space
                else:
                    # 改变起始点的坐标
                    x1 = x2
                    y1 = y2
                    distance -= line_distance  # 长度要减去之前线段的长度
                    break
        return dividing_points
    
    
    def draw(points):
        img = np.zeros((1000, 1000, 3), np.uint8)
        for point in points:
            point = (int(point[0]), int(point[1]))
            cv2.circle(img, point, 4, (0, 0, 255), -1)
    
        cv2.imshow('a', img)
        cv2.waitKey(0)
        cv2.destroyAllWindows()
    
    
    if __name__ == '__main__':
        test_points = [
            [50, 50], [200, 100], [500, 700]
        ]
        draw(test_points)
        # result_points = polyline_get_dividing_points(test_points, 10)
        # print(result_points)
        result_points = polyline_equally_spaced_points(test_points, 20)
        print(result_points)
        draw(result_points)
    
    

    效果

    原始:

    image

    添加等分点后:

    image

    不论你在什么时候开始,重要的是开始之后就不要停止。 不论你在什么时候结束,重要的是结束之后就不要悔恨。
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  • 原文地址:https://www.cnblogs.com/yunhgu/p/15471579.html
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