opencv识别三角形代码（转）

//三角形检测代码
//载入数张包含各种形状的图片，检测出其中的三角形

#include "cv.h"
#include "highgui.h"
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <iostream>

int thresh = 50;
IplImage* img =NULL;
IplImage* img0 = NULL;
CvMemStorage* storage =NULL;
const char * wndname = "三角形识别 Demo";

// 两个向量之间找到角度的余弦值
// from pt0->pt1 and from pt0->pt2
double angle( CvPoint* pt1, CvPoint* pt2, CvPoint* pt0 )
{
 double dx1 = pt1->x - pt0->x;
 double dy1 = pt1->y - pt0->y;
 double dx2 = pt2->x - pt0->x;
 double dy2 = pt2->y - pt0->y;
 return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
}

// 返回图像中找到的轮廓序列
// 序列存储在内存存储器中
CvSeq* findSquares4( IplImage* img, CvMemStorage* storage )
{
 CvSeq* contours;
 int i, c, l, N = 11;
 CvSize sz = cvSize( img->width & -2, img->height & -2 ); 
 
 IplImage* timg = cvCloneImage( img );
 IplImage* gray = cvCreateImage( sz, 8, 1 );
 IplImage* pyr = cvCreateImage( cvSize(sz.width/2, sz.height/2), 8, 3 );
 IplImage* tgray;
 CvSeq* result;
 double s, t;
 // 创建一个空序列用于存储轮廓和角点
 CvSeq* squares = cvCreateSeq( 0, sizeof(CvSeq), sizeof(CvPoint), storage );

 cvSetImageROI( timg, cvRect( 0, 0, sz.width, sz.height ));
 // 过滤噪音
 cvPyrDown( timg, pyr, 7 );
 cvPyrUp( pyr, timg, 7 );
 tgray = cvCreateImage( sz, 8, 1 );

 // find squares in every color plane of the image
 for( c = 0; c < 3; c++ )
 {
  // 提取 the c-th color plane
  cvSetImageCOI( timg, c+1 );
  cvCopy( timg, tgray, 0 );

  // try several threshold levels
  for( l = 0; l < N; l++ )
  {
   // hack: use Canny instead of zero threshold level.
   // Canny helps to catch squares with gradient shading  
   if( l == 0 )
   {
    // apply Canny. Take the upper threshold from slider
    // and set the lower to 0 (which forces edges merging)
    cvCanny( tgray, gray, 0, thresh, 5 );
    // dilate canny output to remove potential
    // holes between edge segments
    cvDilate( gray, gray, 0, 1 );
   }
   else
   {
    // apply threshold if l!=0:
    //     tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
    cvThreshold( tgray, gray, (l+1)*255/N, 255, CV_THRESH_BINARY );
   }

   // 找到所有轮廓并且存储在序列中
   cvFindContours( gray, storage, &contours, sizeof(CvContour),
    CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0) );

   // test each contour
   while( contours )
   {
    // approximate contour with accuracy proportional
    // to the contour perimeter
    result = cvApproxPoly( contours, sizeof(CvContour), storage,
     CV_POLY_APPROX_DP, cvContourPerimeter(contours)*0.02, 0 );
    // 三角形轮廓应当有3个顶点,3条边
    // relatively large area (过滤干扰的轮廓)
    // cvCheckContourConvexity保证是凸面的
    // cvContourArea计算三角形区域面积，去掉一些不相干的区域
    if( result->total == 3 &&
     fabs(cvContourArea(result,CV_WHOLE_SEQ)) > 1000 &&
     fabs(cvContourArea(result,CV_WHOLE_SEQ)) < 100000 &&
     cvCheckContourConvexity(result) )
    {
     

      for( i = 0; i < 3; i++ )
       cvSeqPush( squares,
       (CvPoint*)cvGetSeqElem( result, i ));
    }

    // 继续查找下一个轮廓
    contours = contours->h_next;
   }
  }
 }

 // release all the temporary images
 cvReleaseImage( &gray );
 cvReleaseImage( &pyr );
 cvReleaseImage( &tgray );
 cvReleaseImage( &timg );

 return squares;
}

// the function draws all the squares in the image
void drawSquares( IplImage* img, CvSeq* squares )
{
 CvSeqReader reader;
 IplImage* cpy = cvCloneImage( img );
 int i;

 // initialize reader of the sequence
 cvStartReadSeq( squares, &reader, 0 );

 // read 4 sequence elements at a time (all vertices of a square)
 for( i = 0; i < squares->total; i += 3 )
 {
  CvPoint pt[3], *rect = pt;
  int count = 3;

  // read 3 vertices
  CV_READ_SEQ_ELEM( pt[0], reader );
  CV_READ_SEQ_ELEM( pt[1], reader );
  CV_READ_SEQ_ELEM( pt[2], reader );

  // cvPolyLine函数画出三角形轮廓
  cvPolyLine( cpy, &rect, &count, 1, 1, CV_RGB(0,255,0), 3, CV_AA, 0 );
 }

 // show the resultant image
 cvShowImage( wndname, cpy );
 cvReleaseImage( &cpy );
}

char* names[] = {  "pic1.png", "pic2.png", "pic3.png",
     "pic4.png", "pic5.png", "pic6.png","pic7.png", "pic8.png",
     "pic9.png","pic10.png", "pic11.png", "pic12.png",0 };

int main(int argc, char** argv)
{
 int i, c;
 // create memory storage that will contain all the dynamic data
 storage = cvCreateMemStorage(0);

 for( i = 0; names[i] != 0; i++ )
 {
  img0 = cvLoadImage( names[i], 1 );
  if( !img0 )
  {
   cout<<"不能载入"<<names[i]<<"继续下一张图片"<<endl;
   continue;
  }
  img = cvCloneImage( img0 );
  
  cvNamedWindow( wndname, 1 );

  drawSquares( img, findSquares4( img, storage ) );
  c = cvWaitKey(0);
  // release both images
  cvReleaseImage( &img );
  cvReleaseImage( &img0 );
  // clear memory storage - reset free space position
  cvClearMemStorage( storage );
  if( (char)c == 27 )
   break;
 }

 cvDestroyWindow( wndname );
 return 0;
}