int main()
{
//创建一个用于绘制图像的 空白图
cv::Mat image = cv::Mat::zeros(1024, 19200, CV_8UC3);
//输入拟合点
std::vector<cv::Point> points;
/*points.push_back(cv::Point(500, 158));
points.push_back(cv::Point(105, 98));
points.push_back(cv::Point(155, 160));
points.push_back(cv::Point(212, 220));
points.push_back(cv::Point(248, 260));
points.push_back(cv::Point(320, 300));
points.push_back(cv::Point(350, 360));
points.push_back(cv::Point(412, 400));*/
points.push_back(cv::Point(50, 500));
points.push_back(cv::Point(50, 300));
points.push_back(cv::Point(250, 300));
points.push_back(cv::Point(250, 500));
//将拟合点绘制到空白图上
for (int i = 0; i < points.size(); i++)
{
cv::circle(image, points[i], 5, cv::Scalar(0, 0, 255), 2, 8, 0);
}
cv::Vec4f line_para;
cv::fitLine(points, line_para, cv::DIST_L2, 0, 1e-2, 1e-2);
std::cout << "line_para = " << line_para << std::endl;
//获取点斜式的点和斜率
cv::Point point0;
point0.x = line_para[2];
point0.y = line_para[3];
double k = line_para[1] / line_para[0];
//计算直线的端点(y = k(x - x0) + y0)
cv::Point point1, point2;
point1.x = 20;
point1.y = k*(20 - point0.x) + point0.y;
point2.x = 100;
point2.y = k*(100 - point0.x) + point0.y;
//计算距离point0 20个单位出的点的位置并画出该段线
int step = 20;
Point pt1, pt2;
//后step处的点
pt1.x = point1.x - step;
pt1.y = point1.y - k*step;
//前step处的点
pt2.x = point1.x + step;
pt2.y = point1.y + k*step;
//Rect rect(pt2.x, pt2.y, 40, 40);
cv::circle(image, point1, 5, cv::Scalar(0,255, 0), 2, 8, 0);
waitKey(0);
cv::circle(image,pt1, 5, cv::Scalar(0, 0, 255), 2, 8, 0);
waitKey(0);
cv::circle(image, pt2, 5, cv::Scalar(255, 0, 0), 2, 8, 0);
waitKey(0);
cv::line(image, point1, point2, cv::Scalar(0, 255, 0), 2, 8, 0);
cv::imshow("image", image);
cv::waitKey(0);
return 0;
}
算法实现部分:
int step = 20;
Point pt1, pt2;
//后step处的点
pt1.x = point1.x - step;
pt1.y = point1.y - k*step;
//前step处的点
pt2.x = point1.x + step;
pt2.y = point1.y + k*step;
这里的step为距离的单位,即在本例子中就是距离point1点横坐标的距离为20个单位。-表示在该点的左边,+表示在该点的右边。
该方法适用于所有直线表达式。
图片:
绿点为本例中要实验的点,红点距离该点x坐标-20个单位的点,蓝点距离该点x坐标+20个单位的点。