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cv::fitLine用法
- 定义
- 代码示例
-
- y = x 1直线
- y = -x 1直线
定义
在opencv官方文档定义如下：
代码语言：javascript复制void cv::fitLine(InputArray points,
OutputArray line,
int distType,
double param,
double reps,
double aeps
)
#include <opencv2/imgproc.hpp>
Fits a line to a 2D or 3D point set.
Parameters
points Input vector of 2D or 3D points, stored in std::vector<> or Mat.
line Output line parameters. In case of 2D fitting, it should be a vector of 4 elements (like Vec4f) - (vx, vy, x0, y0), where (vx, vy) is a normalized vector collinear to the line and (x0, y0) is a point on the line. In case of 3D fitting, it should be a vector of 6 elements (like Vec6f) - (vx, vy, vz, x0, y0, z0), where (vx, vy, vz) is a normalized vector collinear to the line and (x0, y0, z0) is a point on the line.
distType Distance used by the M-estimator, see DistanceTypes
param Numerical parameter ( C ) for some types of distances. If it is 0, an optimal value is chosen.
reps Sufficient accuracy for the radius (distance between the coordinate origin and the line).
aeps Sufficient accuracy for the angle. 0.01 would be a good default value for reps and aeps.Jetbrains全家桶1年46，售后保障稳定
代码示例
简而言之，就是利用已有的点拟合直线，本篇只针对使用做简单示例，基于opencv3.4.5, C ； 主要介绍输出参数，
OutputArray line：在二维下为四个元素，前两个为向量（x, y），后两个为拟合直线上的一个点
distType，参考如下：
代码语言：javascript复制//! @see distanceTransform, fitLine
enum DistanceTypes {
DIST_USER = -1, //!< User defined distance
DIST_L1 = 1, //!< distance = |x1-x2| |y1-y2|
DIST_L2 = 2, //!< the simple euclidean distance
DIST_C = 3, //!< distance = max(|x1-x2|,|y1-y2|)
DIST_L12 = 4, //!< L1-L2 metric: distance = 2(sqrt(1 x*x/2) - 1))
DIST_FAIR = 5, //!< distance = c^2(|x|/c-log(1 |x|/c)), c = 1.3998
DIST_WELSCH = 6, //!< distance = c^2/2(1-exp(-(x/c)^2)), c = 2.9846
DIST_HUBER = 7 //!< distance = |x|<c ? x^2/2 : c(|x|-c/2), c=1.345
};param： 默认0，opencv自动优化
reps：0.01精度即可
aeps：建议0.01，0.01 would be a good default value…
y = x 1直线
向量（0.707107，0.707107）如图下
std::vector<cv::Point2f> input_pts; input_pts.emplace_back(1, 2); input_pts.emplace_back(2, 3); cv::Vec4f calc_line; cv::fitLine(input_pts, calc_line, cv::DIST_L2, 0, 0.01, 0.01); std::cout << "calc_line[0]=" << calc_line[0] << "ncalc_line[0]=" << calc_line[1] << "ncalc_line[0]=" << calc_line[2] << "ncalc_line[0]=" << calc_line[3] << std::endl;
控制台输出
代码语言：javascript复制calc_line[0]=0.707107
calc_line[0]=0.707107
calc_line[0]=1.5
calc_line[0]=2.5y = -x 1直线
向量（0.707107，-0.707107）
std::vector<cv::Point2f> input_pts; input_pts.emplace_back(1, 2); input_pts.emplace_back(2, 1); cv::Vec4f calc_line; cv::fitLine(input_pts, calc_line, cv::DIST_L2, 0, 0.01, 0.01); std::cout << "calc_line[0]=" << calc_line[0] << "ncalc_line[0]=" << calc_line[1] << "ncalc_line[0]=" << calc_line[2] << "ncalc_line[0]=" << calc_line[3] << std::endl;
calc_line[0]=0.707107
calc_line[0]=-0.707107
calc_line[0]=1.5
calc_line[0]=1.5Enjoy~
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