arcLength函数

1、arcLength函数

函数的作用

主要是计算图像轮廓的周长、

2、函数调用形式

C++: double arcLength(InputArray curve, bool closed)

参数详解：

InputArray curve：表示图像的轮廓

bool closed：表示轮廓是否封闭的

3、一般图像轮廓矩也可以算出图像的周长和面积

opencv代码：

    
    
#include “opencv2/highgui/highgui.hpp”
#include “opencv2/imgproc/imgproc.hpp”
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace cv;
using namespace std;

Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);

/// 函数声明
void thresh_callback(int, void* );

/** @主函数 */
int main( int argc, char** argv )
{
/// 读入原图像, 返回3通道图像数据
src = imread( argv[ 1], 1 );

/// 把原图像转化成灰度图像并进行平滑
cvtColor( src, src_gray, CV_BGR2GRAY );
blur( src_gray, src_gray, Size( 3, 3) );

/// 创建新窗口
char* source_window = “Source”;
namedWindow( source_window, CV_WINDOW_AUTOSIZE );
imshow( source_window, src );

createTrackbar( ” Canny thresh:”, “Source”, &thresh, max_thresh, thresh_callback );
thresh_callback( 0, 0 );

waitKey( 0);
return( 0);
}

/** @thresh_callback 函数 */
void thresh_callback(int, void* )
{
Mat canny_output;
vector< vector<Point> > contours;
vector<Vec4i> hierarchy;

/// 使用Canndy检测边缘
Canny( src_gray, canny_output, thresh, thresh* 2, 3 );
/// 找到轮廓
findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point( 0, 0) );

/// 计算矩
vector<Moments> mu(contours.size() );
for( int i = 0; i < contours.size(); i++ )
{ mu[i] = moments( contours[i], false ); }

/// 计算中心矩:
vector<Point2f> mc( contours.size() );
for( int i = 0; i < contours.size(); i++ )
{ mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 ); }

/// 绘制轮廓
Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
for( int i = 0; i< contours.size(); i++ )
{
Scalar color = Scalar( rng.uniform( 0, 255), rng.uniform( 0, 255), rng.uniform( 0, 255) );
drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
circle( drawing, mc[i], 4, color, -1, 8, 0 );
}

/// 显示到窗口中
namedWindow( “Contours”, CV_WINDOW_AUTOSIZE );
imshow( “Contours”, drawing );

/// 通过m00计算轮廓面积并且和OpenCV函数比较
printf( “\t Info: Area and Contour Length \n”);
for( int i = 0; i< contours.size(); i++ )
{
printf( ” * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n”, i, mu[i].m00, contourArea(contours[i]), arcLength( contours[i], true ) );
Scalar color = Scalar( rng.uniform( 0, 255), rng.uniform( 0, 255), rng.uniform( 0, 255) );
drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
circle( drawing, mc[i], 4, color, -1, 8, 0 );
}
}
    
    

            </div>

1、arcLength函数

函数的作用

主要是计算图像轮廓的周长、

2、函数调用形式

C++: double arcLength(InputArray curve, bool closed)

参数详解：

InputArray curve：表示图像的轮廓

bool closed：表示轮廓是否封闭的

3、一般图像轮廓矩也可以算出图像的周长和面积

opencv代码：

  
  
#include “opencv2/highgui/highgui.hpp”
#include “opencv2/imgproc/imgproc.hpp”
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace cv;
using namespace std;

Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);

/// 函数声明
void thresh_callback(int, void* );

/** @主函数 */
int main( int argc, char** argv )
{
/// 读入原图像, 返回3通道图像数据
src = imread( argv[ 1], 1 );

/// 把原图像转化成灰度图像并进行平滑
cvtColor( src, src_gray, CV_BGR2GRAY );
blur( src_gray, src_gray, Size( 3, 3) );

/// 创建新窗口
char* source_window = “Source”;
namedWindow( source_window, CV_WINDOW_AUTOSIZE );
imshow( source_window, src );

createTrackbar( ” Canny thresh:”, “Source”, &thresh, max_thresh, thresh_callback );
thresh_callback( 0, 0 );

waitKey( 0);
return( 0);
}

/** @thresh_callback 函数 */
void thresh_callback(int, void* )
{
Mat canny_output;
vector< vector<Point> > contours;
vector<Vec4i> hierarchy;

/// 使用Canndy检测边缘
Canny( src_gray, canny_output, thresh, thresh* 2, 3 );
/// 找到轮廓
findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point( 0, 0) );

/// 计算矩
vector<Moments> mu(contours.size() );
for( int i = 0; i < contours.size(); i++ )
{ mu[i] = moments( contours[i], false ); }

/// 计算中心矩:
vector<Point2f> mc( contours.size() );
for( int i = 0; i < contours.size(); i++ )
{ mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 ); }

/// 绘制轮廓
Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
for( int i = 0; i< contours.size(); i++ )
{
Scalar color = Scalar( rng.uniform( 0, 255), rng.uniform( 0, 255), rng.uniform( 0, 255) );
drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
circle( drawing, mc[i], 4, color, -1, 8, 0 );
}

/// 显示到窗口中
namedWindow( “Contours”, CV_WINDOW_AUTOSIZE );
imshow( “Contours”, drawing );

/// 通过m00计算轮廓面积并且和OpenCV函数比较
printf( “\t Info: Area and Contour Length \n”);
for( int i = 0; i< contours.size(); i++ )
{
printf( ” * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n”, i, mu[i].m00, contourArea(contours[i]), arcLength( contours[i], true ) );
Scalar color = Scalar( rng.uniform( 0, 255), rng.uniform( 0, 255), rng.uniform( 0, 255) );
drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
circle( drawing, mc[i], 4, color, -1, 8, 0 );
}
}
  
  

            </div>