cv2.fitline_pr自动抽帧

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.

//! @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
};

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

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