opencv 检测直线、圆、矩形

opencv 检测直线、圆、矩形

检测直线：cvHoughLines，cvHoughLines2

检测矩形：opencv中没有对应的函数，下面有段代码可以检测矩形，是通过先找直线，然后找到直线平行与垂直的四根线。

检测直线代码：

#include <cv.h>

#include <highgui.h>

#include <math.h>

int main(int argc, char** argv)

{

   const char* filename = argc >= 2 ? argv[1] : "pic1.png";

   IplImage* src = cvLoadImage( filename, 0 );

   CvMemStorage* storage = cvCreateMemStorage(0);

   

   dst = cvCreateImage( cvGetSize(src), 8, 1 );

   color_dst = cvCreateImage( cvGetSize(src), 8, 3 );

   

   cvCanny( src, dst, 50, 200, 3 );

   cvCvtColor( dst, color_dst, CV_GRAY2BGR );

#if 0

   lines = cvHoughLines2( dst, storage, CV_HOUGH_STANDARD, 1, CV_PI/180, 100, 0, 0 );

   for( i = 0; i < MIN(lines->total,100); i++ )

   float* line = (float*)cvGetSeqElem(lines,i);

       float rho = line[0];

       float theta = line[1];

       double a = cos(theta), b = sin(theta);

       double x0 = a*rho, y0 = b*rho;

       pt1.x = cvRound(x0 + 1000*(-b));

       pt1.y = cvRound(y0 + 1000*(a));

       pt2.x = cvRound(x0 - 1000*(-b));

       pt2.y = cvRound(y0 - 1000*(a));

       cvLine( color_dst, pt1, pt2, CV_RGB(255,0,0), 3, CV_AA, 0 );

#else

   lines = cvHoughLines2( dst, storage, CV_HOUGH_PROBABILISTIC, 1, CV_PI/180, 50, 50, 10 );

   for( i = 0; i < lines->total; i++ )

       CvPoint* line = (CvPoint*)cvGetSeqElem(lines,i);

       cvLine( color_dst, line[0], line[1], CV_RGB(255,0,0), 3, CV_AA, 0 );

#endif

   cvNamedWindow( "Source", 1 );

   cvShowImage( "Source", src );

   cvNamedWindow( "Hough", 1 );

   cvShowImage( "Hough", color_dst );

}

检测圆代码：

#include <cv.h>

#include <highgui.h>

#include <math.h>

int main(int argc, char** argv)

{

   if( argc == 2 && (img=cvLoadImage(argv[1], 1))!= 0)

       IplImage* gray = cvCreateImage( cvGetSize(img), 8, 1 );

       CvMemStorage* storage = cvCreateMemStorage(0);

       cvCvtColor( img, gray, CV_BGR2GRAY );

       cvSmooth( gray, gray, CV_GAUSSIAN, 9, 9 ); // smooth it, otherwise a lot of false circles may be detected

       CvSeq* circles = cvHoughCircles( gray, storage, CV_HOUGH_GRADIENT, 2, gray->height/4, 200, 100 );

       for( i = 0; i < circles->total; i++ )

            float* p = (float*)cvGetSeqElem( circles, i );

            cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 3, CV_RGB(0,255,0), -1, 8, 0 );

            cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(255,0,0), 3, 8, 0 );

       cvNamedWindow( "circles", 1 );

       cvShowImage( "circles", img );

}