本章内容:

1. 轮廓查找

2. 绘制轮廓

3. 凸包

4.最小外接矩形

5.最小外接圆

6.最小外接椭圆

1.搜索轮廓

2.绘制轮廓

输出结果

3.凸包

输出结果

4.最小外接矩形

输出结果

5.最小外接圆

输出结果：

6. 最小外接椭圆

输出结果

代码

#include <ostream>

#include <opencv.hpp>

#include <math.h>

int main(int argc, char *argv[])

{

/*

本章内容:

1. 轮廓查找

2. 绘制轮廓

3. 凸包

4.最小外接矩形

5.最小外接圆

6.最小外接椭圆

*/

cv::String fileName = "/home/wang/dev/Image/QT.jpg";

cv::String fileName1 = "/home/wang/dev/Image/hei.png";

cv::Mat src = cv::imread(fileName);

cv::Mat src1 = cv::imread(fileName1);

if(src.data == NULL){

printf("图像读入失败\n");

return -1;

}

/* 轮廓查找

* api接口: CV_EXPORTS_W void findContours( InputArray image, OutputArrayOfArrays contours,

OutputArray hierarchy, int mode,

int method, Point offset = Point());

参数分析:

@param contours. std::vector<std::vector<cv::Point> >

@param hierarchy Optional output vector

@param mode Contour retrieval mode, see #RetrievalModes

@param method Contour approximation method, see #ContourApproximationModes

enum RetrievalModes{

RETR_EXTERNAL = 0,

RETR_LIST = 1,

RETR_CCOMP = 2,

RETR_TREE = 3,

RETR_FLOODFILL = 4

}

enum ContourApproximationModes{

enum ContourApproximationModes {

CHAIN_APPROX_NONE = 1,

CHAIN_APPROX_SIMPLE = 2,

CHAIN_APPROX_TC89_L1 = 3,

CHAIN_APPROX_TC89_KCOS = 4

}

*/

cv::imshow("src",src);

cv::Mat dstCany;

cv::Mat gray;

cv::cvtColor(src,gray,cv::COLOR_BGR2GRAY);

cv::Canny(gray,dstCany,50,150);

std::vector<std::vector<cv::Point>> contours;

std::vector<cv::Vec4i> hierarchy;

cv::findContours(dstCany,contours,hierarchy,cv::RETR_TREE,cv::CHAIN_APPROX_SIMPLE,cv::Point(0,0));

cv::RNG rng(1234);

cv::Mat dst(src.size(),src.type());

/* 绘制轮廓

api接口: CV_EXPORTS_W void drawContours( InputOutputArray image, InputArrayOfArrays contours,

int contourIdx, const Scalar& color,

int thickness = 1, int lineType = LINE_8,

InputArray hierarchy = noArray(),

int maxLevel = INT_MAX, Point offset = Point() );

参数分析:

@param contourIdx Parameter indicating a contour to draw. If it is negative, all the contours are drawn.

@param color Color of the contours.

*/

for(int i=0; i <contours.size();i++){

cv::Scalar color = cv::Scalar(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255));

cv::drawContours(dst,contours,i,color,4);

}

/* 3.凸包

* api接口:CV_EXPORTS_W void convexHull( InputArray points, OutputArray hull,

bool clockwise = false, bool returnPoints = true );

@param points 二维点集，vector

@param hull Output convex hull. vector<Point>

*/

std::vector<cv::Point> hull;

cv::convexHull(contours[0],hull);

for(int i=0;i<hull.size();i++){

cv::line(dst,hull[i],hull[(i+1)%hull.size()],cv::Scalar(0,255,0),4);

}

/* 4.最小外接矩形

apie接口: CV_EXPORTS_W RotatedRect minAreaRect( InputArray points );

*/

cv::RotatedRect rect = cv::minAreaRect(contours[1]);

cv::Point2f Ps[4];

rect.points(Ps);

for(int i=0;i<4;i++) cv::line(dst,Ps[i],Ps[(i+1)%4],cv::Scalar(0,0,255),4);

/* 5.最小外接圆

* api接口: CV_EXPORTS_W void minEnclosingCircle( InputArray points,

CV_OUT Point2f& center, CV_OUT float& radius );

*/

cv::Point2f pc;

float radius;

cv::minEnclosingCircle(contours[2],pc,radius);

cv::circle(dst,pc,radius,cv::Scalar(255,0,0),4);

/*6.最小外接椭圆

* api接口:CV_EXPORTS_W RotatedRect fitEllipse( InputArray points );

*/

cv::RotatedRect ell = cv::fitEllipse(contours[1]);

cv::ellipse(dst,ell,cv::Scalar(0,255,255),4);

cv::imshow("dst",dst);

cv::waitKey(0);

return 1;

}