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Jetbrains全家桶1年46，售后保障稳定

定义

在opencv官方文档定义如下：

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：

  //! @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

控制台输出

calc_line[0]=0.707107
calc_line[0]=0.707107
calc_line[0]=1.5
calc_line[0]=2.5

y = -x + 1直线

向量（0.707107，-0.707107）

calc_line[0]=0.707107
calc_line[0]=-0.707107
calc_line[0]=1.5
calc_line[0]=1.5

Enjoy~