OpenCV：判定曲线为弧线的简单方法
Posted wishchin
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借鉴了一个前同事的一个代码段（良心代码），功能为判定曲线为弧线，并且给出拟合度；
代码段：
//寻找所有canny 弧
int findArcsOfAllCanny( cv::Mat &inMatCanny,
std::vector<std::vector<std::pair< cv::Point, float> > > &circlesPupil, cv::RotatedRect &ecf, int method)
//简单方法，链接各个连通域的质心，拼凑成一个连通域
std::vector<std::vector<cv::Point> > all_contours;
std::vector<cv::Vec4i> hierarchy;
cv::findContours(inMatCanny, all_contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_NONE);//连续点
int minSize = 20;
int maxSize =1000;
#ifdef SHOW_TEMP
cv::Mat canvas = cv::Mat::zeros(inMatCanny.rows, inMatCanny.cols, CV_8UC3);
cv::bitwise_not(canvas, canvas);
for (int i = 0; i < all_contours.size(); i++)
if (all_contours[i].size() > minSize)
cv::Mat canvas2 = canvas.clone();
cv::drawContours(canvas, all_contours, i, cv::Scalar(0, 0, 255));
cv::imshow("canvasEdgeSrc", canvas); cv::waitKey(1);
#endif
//在找出所有的弧，并计算出弧度
int kSegLen = 6;//设定固定寻找弦长度
if ( 2== method)
kSegLen = 10;
else
kSegLen = 8;
std::vector<std::vector<cv::Point> > edgesValid(0);
for (int i = 0; i < all_contours.size(); i++)
if (all_contours[i].size() > minSize && all_contours[i].size() < maxSize )
//添加
std::vector<std::vector<cv::Point> > curves = divideCurveByCurvity( all_contours[i], kSegLen );
for ( int k=0;k< curves.size();++k )
if ( curves[k].size()>=5 )
edgesValid.push_back(curves[k]); //
//在找出所有的弧，并计算出弧度
circlesPupil.resize(0);
int counter = edgesValid.size();
std::vector<std::vector<cv::Point> > convex_contour(counter);//(all_contours.size() );
//std::vector<cv::Point> approx_poly;//影响了后面的程序
std::vector<int> apdNum(counter);//(all_contours.size() );
std::vector<cv::RotatedRect > rects;
std::vector<float> sigmas(counter);//(all_contours.size() );
//float mv = 99999; int uind = 0;
//1.发现凸边缘
int idx = 0;
for (int i = 0; i < edgesValid.size(); i++)
float mv = 99999; int uind = 0;
std::vector<cv::Point> approx_poly;
bool showTemp = true;
if (showTemp)
cv::Mat canvas( 200, 200, CV_8UC3 );
for (int k = 0; k < edgesValid[i].size(); ++k)
canvas.at<cv::Vec3b>(edgesValid[i][k].y, edgesValid[i][k].x) = cv::Vec3b(255, 0, 0);
cv::imshow("edgesValid", canvas); cv::waitKey(10);
cv::convexHull(edgesValid[i], convex_contour[i], false, true);//放大时插值图片可否保持凸包情形
if (showTemp)
cv::Mat canvas(200, 200, CV_8UC3);
for (int k = 0; k < convex_contour[i].size(); ++k)
canvas.at<cv::Vec3b>(convex_contour[i][k].y, convex_contour[i][k].x) = cv::Vec3b(255, 0, 0);
cv::imshow("convex_contour", canvas); cv::waitKey(10);
float ts = isCircle(convex_contour[i]);
sigmas[i] = ts;
cv::RotatedRect rr = cv::minAreaRect(convex_contour[i]);
rects.push_back(rr);
cv::approxPolyDP(convex_contour[i], approx_poly, 1, true);
apdNum[i] = approx_poly.size();
if (mv > ts && apdNum[i] >= 10)
mv = ts;
uind = i;
//2.判定所有弧
int minPs = 5;
std::vector<std::vector<cv::Point2f> > arc_pts(0);
std::vector<int> ulist, uInds;
for (int i = 0; i < convex_contour.size(); ++i)
std::vector<cv::Point2f> arc_pt(0);
bool isFind = findArc2(convex_contour[i], arc_pt, ulist);//函数有问题，对于一个点/两个相同的点 也判断为弧！
if (isFind && arc_pt.size() >= minPs) //if (isFind)
arc_pts.push_back(arc_pt);
uInds.push_back(i);
/
//2.1 判断弧的拟合度
for (int i = 0; i < arc_pts.size(); ++i)
sortPoints(arc_pts[i]);
sampleArc(arc_pts[i]);
circlesPupil.resize(uInds.size());
if (circlesPupil.size() < 1) return 0;
for (int i = 0; i < uInds.size(); ++i)
circlesPupil[i].resize(convex_contour[uInds[i]].size());
for (int j = 0; j < convex_contour[uInds[i]].size(); ++j)
circlesPupil[i][j].first = convex_contour[uInds[i]][j];
#ifdef SHOW_TEMP
cv::Mat canvasV = cv::Mat::zeros(inMatCanny.rows, inMatCanny.cols, CV_8UC3);
cv::bitwise_not(canvasV, canvasV);
for (int i = 0; i < circlesPupil.size(); i++)
for (int j = 0; j < circlesPupil[i].size(); j++)
cv::circle(canvasV, circlesPupil[i][j].first, 1, (0, 0, 255), 1, 8, 0);
cv::imshow("canvasValid", canvasV); cv::waitKey(1);
#endif
return 1;
//findArcsOfAllCannybool findArc2(const std::vector<cv::Point>& hpts, std::vector<cv::Point2f>& arc_pts, std::vector<int>& inds)
arc_pts.clear();
if (hpts.size() <= 2) return false;
std::vector<edgePoint>epts(hpts.size());
for (int i = 0; i < hpts.size(); i++)
cv::Vec3d v1, v2, v3;
if (i == 0)
v1 = cv::Vec3d(hpts[0].x - hpts[hpts.size() - 1].x,
hpts[0].y - hpts[hpts.size() - 1].y, 0);
v2 = cv::Vec3d(hpts[1].x - hpts[0].x,
hpts[1].y - hpts[0].y, 0);
else if (i == hpts.size() - 1)
v1 = cv::Vec3d(hpts[i].x - hpts[i - 1].x,
hpts[i].y - hpts[i - 1].y, 0);
v2 = cv::Vec3d(hpts[0].x - hpts[i].x,
hpts[0].y - hpts[i].y, 0);
else
v1 = cv::Vec3d(hpts[i].x - hpts[i - 1].x,
hpts[i].y - hpts[i - 1].y, 0);
v2 = cv::Vec3d(hpts[i + 1].x - hpts[i].x,
hpts[i + 1].y - hpts[i].y, 0);
float len1 = sqrt(v1[0] * v1[0] + v1[1] * v1[1] + v1[2] * v1[2]);
float len2 = sqrt(v2[0] * v2[0] + v2[1] * v2[1] + v2[2] * v2[2]);
v1[0] /= len1; v1[1] /= len1; v1[2] /= len1;
v2[0] /= len2; v2[1] /= len2; v2[2] /= len2;
v3 = VecCross(v1, v2);
epts[i].angle = sqrt(v3[0] * v3[0] + v3[1] * v3[1] + v3[2] * v3[2]);
epts[i].ind = i;
epts[i].pos = hpts[i];
cv::sort(epts, cmp);
inds.push_back(epts[0].ind);
for (int i = 1; i < epts.size(); i++)
float len = epts[i] * epts[0];//运算符重载失效，为何？
//float len =0;
//edgePoint a = epts[i]; const edgePoint b= epts[0];
//len = sqrt((double)(a.pos.x - b.pos.x) * (a.pos.x - b.pos.x) +(a.pos.y - b.pos.y) * (a.pos.y - b.pos.y));
if (len <= 10)
continue;
else
inds.push_back(epts[i].ind);
break;
if (inds.size() <= 1) return false;
//inds.push_back(epts[1].ind);
int leftlen = std::max(inds[0], inds[1]) - std::min(inds[0], inds[1]);
int rightlen = hpts.size() - leftlen;
if (inds[0] < hpts.size() && inds[1] < hpts.size())//附件！wishchin!!!排除大下标
if (leftlen > rightlen)
for (int i = 0; i < hpts.size(); i++)
if (i >= std::min(inds[0], inds[1]) && i <= std::max(inds[0], inds[1]))
if (!cvWish::line::isLinear(hpts[inds[0]], hpts[inds[1]], hpts[i]))
arc_pts.push_back(hpts[i]);
else
for (int i = 0; i < hpts.size(); i++)
if (i > std::min(inds[0], inds[1]) && i < std::max(inds[0], inds[1]))
//arc_pts.push_back(hpts[i]);
else
//std::cout<<"id = "<<i<<endl;
if (!cvWish::line::isLinear(hpts[inds[0]], hpts[inds[1]], hpts[i]))
arc_pts.push_back(hpts[i]);
arc_pts.push_back(hpts[inds[0]]);
arc_pts.push_back(hpts[inds[1]]);
return true;
else return false;
//findArc2
inline cv::Vec3d VecCross(const cv::Vec3d& p1, const cv::Vec3d& p2)
return cv::Vec3d(
p1[1]*p2[2]-p1[2]*p2[1],p1[2]*p2[0]-p1[0]*p2[2],
p1[0]*p2[1]-p1[1]*p2[0]
);
//判断是否在一条线上
bool isLinear(const cv::Point2f& a, const cv::Point2f& b, const cv::Point2f& c)
cv::Point2f a1 = b - a;
float alen = b * a;
if (alen <= 0.5)
return true;
a1.x /= alen; a1.y /= alen;
cv::Point2f a2 = c - a;
float alen2 = c * a;
if (alen2 <= 0.5)
return true;
a2.x /= alen2; a2.y /= alen2;
cv::Vec3d cc = VecCross(cv::Vec3d(a1.x, a1.y, 0), cv::Vec3d(a2.x, a2.y, 0));
float len = abs(cc[2]);
//std::cout<<"len = "<<len<<endl;
if (len <= 0.02)
return true;
return false;
; //判断是否是圆//方法不怎么地！
float isCircle(const std::vector<cv::Point>& hull)
cv::RotatedRect r = cv::minAreaRect(hull);
std::vector<cv::Point2f>pts;
getRectBottomLine(r, pts);
cv::Point2f center = cv::Point2f((pts[0].x + pts[1].x) / 2.0, (pts[0].y + pts[1].y) / 2.0);
float mean_v = 0;
std::vector<float>lens(hull.size());
for (int i = 0; i < hull.size(); i++)
float tlen = sqrt((hull[i].x - center.x) * (hull[i].x - center.x) +
(hull[i].y - center.y) * (hull[i].y - center.y));
lens[i] = tlen;
mean_v += tlen;
mean_v /= hull.size();
float sigma = 0.0;
for (int i = 0; i < hull.size(); i++)
sigma += (lens[i] - mean_v) * (lens[i] - mean_v);
sigma = sqrt(sigma);
sigma /= hull.size();
return sigma;
//isCircle void getRectBottomLine(const cv::RotatedRect& r, std::vector<cv::Point2f>& pts)
pts.resize(2);
//std::vector<cv::Point2f>pts;
//cv::Point2f * pp = new cv::Point2f(4);
//r.points(pp);
//std::vector<cv::Point2f> pp(4);// = new cv::Point2f(4);
cv::Point2f pp[4];
r.points(pp);
float mid_x = 0;
for (int i = 0; i < 4; i++)
mid_x += pp[i].x;
mid_x /= 4;
float lmax = -99999, rmax = -99999;
int lu = 0, ru = 0;
for (int i = 0; i < 4; i++)
if (pp[i].x < mid_x)
if (lmax < pp[i].y)
lmax = pp[i].y;
lu = i;
else if (pp[i].x >= mid_x)
if (rmax < pp[i].y)
rmax = pp[i].y;
ru = i;
//cv::Point2f pSpl;
pts[0].x = pp[lu].x; pts[0].y = pp[lu].y;
//cv::Point2f pSpr =pp[ru];
pts[1].x = pp[ru].x; pts[1].y = pp[ru].y;
//pts.push_back(pp[lu]);
//pts.push_back(pp[ru]);
//pts.push_back(pSpl );
//pts.push_back(pSpr );
//delete [] pp;
return;
//getRectBottomLine//排序点集；不使用qsort//仅用于寻找 合适的 弧
void sortPoints( std::vector<cv::Point2f>& pts )
int pSize = pts.size();
cv::Point2f LeftPoint = pts[pSize-1];
cv::Point2f RightPoint = pts[pSize-2];
if(LeftPoint.x > RightPoint.x)
swapPoint(LeftPoint , RightPoint);
int mSize = pSize / 2;
cv::Point2f mPoint = pts[mSize];
int caseFlag = 1;
if( mPoint.y < std::min( LeftPoint.y , RightPoint.y ) )
caseFlag = 2;
std::vector<cv::Point2f> newpts;
std::vector<int>visited(pSize-2, 0);
if(caseFlag == 1)
newpts.push_back(RightPoint);
else
newpts.push_back(LeftPoint);
for(int i=0;i<pSize-2;i++)
float dis = 9999.0;
int uind = 0;
cv::Point2f pTop = newpts[newpts.size()-1];
for(int j=0;j<pSize-2;j++)
if(!visited[j])
float dis_j = pts[j] * pTop;
if(dis > dis_j)
dis = dis_j;
uind = j;
newpts.push_back(pts[uind]);
visited[uind] = 1;
if(caseFlag == 1)
newpts.push_back(LeftPoint);
else
newpts.push_back(RightPoint);
pts.clear();
pts = newpts;
return;
inline void swapPoint(cv::Point2f& a, cv::Point2f& b)
cv::Point2f c;
c = b; b= a; a = c;
//确定弧的弧的相似性质
void sampleArc(std::vector<cv::Point2f>& arc_points)
std::vector<cv::Point2f> new_arc;
std::vector<float> arc_dis;
float max_dis = 99999; int uind = 0;
for (int i = 1; i < arc_points.size(); i++)
float tdis = arc_points[i] * arc_points[i - 1];
arc_dis.push_back(tdis);
if (max_dis > tdis)
max_dis = tdis;
uind = i;
for (int i = 0; i < arc_dis.size(); i++)
int sampleNum = floor(arc_dis[i] / max_dis);
cv::Point2f n = arc_points[i + 1] - arc_points[i];
float nLen = arc_points[i + 1] * arc_points[i];
n.x /= nLen; n.y /= nLen;
for (int j = 0; j < sampleNum; j++)
cv::Point2f tp = arc_points[i];
tp.x += j * max_dis * n.x;
tp.y += j * max_dis * n.y;
new_arc.push_back(tp);
cv::Point2f ltp = arc_points[i];
ltp.x += sampleNum * max_dis * n.x;
ltp.y += sampleNum * max_dis * n.y;
float tLen = ltp * arc_points[i + 1];
if (tLen < 0.5 * max_dis)
else
new_arc.push_back(ltp);
float lastDis = arc_points[arc_points.size() - 1] * new_arc[new_arc.size() - 1];
if (lastDis < 0.5 * max_dis)
new_arc[new_arc.size() - 1] = arc_points[arc_points.size() - 1];
else
new_arc.push_back(arc_points[arc_points.size() - 1]);
arc_points.clear();
arc_points = new_arc;
分割弧线的方法：
//根据曲率断开曲线-在曲线首尾处也需要判断是否连接！
std::vector<std::vector<cv::Point> > divideCurveByCurvity( std::vector<cv::Point> &curve, const int k)
std::vector<std::vector<cv::Point> > curves;
//拟合椭圆的效果不好，不能贴合边，而是每个点最小二乘
//cv::RotatedRect ec;
//if ( curve.size()>5 )
// ec = cv::fitEllipse(curve);
// cv::Mat canvas(80, 80, CV_8UC3);
// cv::ellipse(canvas, ec, cv::Scalar(0, 0, 255), 1, 8);
// cv::imshow("ellipse", canvas); cv::waitKey(100);
//
bool showTemp = true;
if ( showTemp && curve.size() >= 5 )
cv::Mat canvas( 200, 200, CV_8UC3 );
for ( int i = 0; i < curve.size(); ++i )
canvas.at<cv::Vec3b>(curve[i].y, curve[i].x) = cv::Vec3b(255, 0, 0);
cv::imshow("curveDiscre", canvas); cv::waitKey(10);
cv::imshow("curveDiscre", canvas); cv::waitKey(10);
int numCurve = 0;
int L = curve.size();
std::vector<double> curvitys;
std::vector<bool > isArcs;
std::vector<double> dis2ps;
bool useCurvity = true;
//const int k = 9;//选取计算曲率的曲线长度,原始图选择6可以
//使用曲率半径或许更好
if ( curve.size()>5 )
curve[0]; curve[curve.size()-1];
int i = 0;
//for (auto ptr = curve.begin(); ptr != curve.end(),i< curve.size(); ++ptr,++i)
for ( ; i< curve.size(); ++i )
std::vector<cv::Point> curveSeg;
if ( useCurvity )
//curveSeg.push_back(cv::Point(curve[(i) % L]));
//curveSeg.push_back(cv::Point(curve[(1 + i) % L]));
//curveSeg.push_back(cv::Point(curve[(2 + i) % L]));
//curveSeg.push_back(cv::Point(curve[(3 + i) % L]));
//curveSeg.push_back(cv::Point(curve[(4 + i) % L]));
for (int j = 0; j < k; ++j)
curveSeg.push_back(cv::Point(curve[(i+j) % L]));
double curvity = 0;//
bool isArc = false;
curvity = getCurvity( curveSeg, isArc);
//curvity = getCurvityR(curveSeg);//使用曲率半径//效果也不好，必须有负值！
curvitys.push_back(curvity);
isArcs.push_back( isArc );
else//使用距离截断
double dis2p = cvWish::disCv(cv::Point(curve[(i) % L]), cv::Point(curve[(1+i) % L]));
dis2ps.push_back(dis2p);
if ( useCurvity )
//根据曲率判断是否断开，这与曲线的曲率均值密切相关
double disCrThres = 0.12;//与R半径相关，在大于0.1的时候断开，即表示为弯道//判断是否为弧在下一步
//bool isChange = false;
//bool isExcess = false;
bool isDown = false;//可能有冗余，或者多不过比少一个安全
for ( i = 0; i < curvitys.size(); ++i )
if (curvitys[i] < disCrThres )
if ( !isDown)
isDown = true;
numCurve += 1;//只数分开的段数，同时表示有效的段数
else//isChange = false;
else
isDown = false;
//for
int pos = -1;//分段
if (numCurve > 0)
curves.resize(numCurve);
else
curves.resize(1);
isDown = false;//需要重新初始化？
for ( i = 0; i < curvitys.size(); ++i )
if ( curvitys[i] < disCrThres )
if (!isDown)
isDown = true;
pos += 1;//注意0和1
else //isDown = false;
curves[pos].push_back(cv::Point(curve[(i) % L]));
else
isDown = false;
//for
else
//根据距离判断是否断开
double disThres = 8;//与R半径相关，为了避免45度时候断开
for (i = 0; i < dis2ps.size(); ++i)
if (dis2ps[i] > disThres)
numCurve += 1;
int pos = 0;
if (numCurve > 0)
curves.resize(numCurve);
else
curves.resize(1);
for (i = 0; i < dis2ps.size(); ++i)
if (dis2ps[i] > disThres)
pos += 1;
pos %= numCurve;
curves[pos].push_back(cv::Point(curve[(i) % L]));
showTemp = true;
if ( showTemp )
for (int n = 0; n < curves.size(); ++n)
cv::Mat canvas(200, 200, CV_8UC3);
for (int i = 0; i < curves[n].size(); ++i)
canvas.at<cv::Vec3b>(curves[n][i].y, curves[n][i].x) = cv::Vec3b(255, 0, 0);
cv::imshow("curveDiscreSeg", canvas); cv::waitKey(10);
return curves;
//divideCurveByCurvitycurvity = getCurvity( curveSeg, isArc);函数在上一篇文章中：https://blog.csdn.net/wishchin/article/details/83447712
图片检测结果：
勘误：数据结构
struct edgePoint
int ind;
cv::Point2f pos;
float angle;
public:
edgePoint(const int& _ind , const cv::Point2f& _pos, const double& _angle): ind(_ind),
pos(_pos) , angle(_angle)
edgePoint()
;cmp函数：
inline bool cmp(edgePoint a, edgePoint b)
return a.angle > b.angle;
inline cv::Vec3d VecCross(const cv::Vec3d& p1, const cv::Vec3d& p2)
return cv::Vec3d(
p1[1]*p2[2]-p1[2]*p2[1],p1[2]*p2[0]-p1[0]*p2[2],
p1[0]*p2[1]-p1[1]*p2[0]
);
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