光流法源代码：关键函数详解与实现

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#include "_cv.h"
#include <float.h>
#include <stdio.h>

namespace cv
{

void calcOpticalFlowPyrLK( const Mat& prevImg, const Mat& nextImg,
                           const vector<Point2f>& prevPts,
                           vector<Point2f>& nextPts,
                           vector<uchar>& status, vector<float>& err,
                           Size winSize, int maxLevel,
                           TermCriteria criteria,
                           double derivLambda,
                           int flags )
{
    derivLambda = std::min(std::max(derivLambda, 0.), 1.);
    double lambda1 = 1. - derivLambda, lambda2 = derivLambda;
    const int derivKernelSize = 3;
    const float deriv1Scale = 0.5f/4.f;