OpenCV计算两条平行线之间的距离

代码来自www.opencvchina.com

#include "cv.h"
#include "highgui.h"
#include "cxcore.h"
#include <stdlib.h>
#include <stdio.h>

#ifndef LINESDISHEADER

#define LINESDISHEADER

//对输入图像进行细化
void ThinImage(IplImage* src, IplImage* dst, int iterations=1);

//获取图像上的轮廓 坐标 
void GetContoursPoints(IplImage* src , CvMat** LinePoints);

#endif

#include "LinesDis.h"


//对输入图像进行细化
void ThinImage(IplImage* src, IplImage* dst, int iterations)
{
 CvSize size = cvGetSize(src);

 cvCopy(src, dst);//拷贝一个数组给另一个数组
    int n = 0,i = 0,j = 0;
 for(n=0; n<iterations; n++)
 {
IplImage* t_image;
 
 t_image = cvCloneImage(dst);
  for(i=0; i<size.height;  i++)
  {
   for(int j=0; j<size.width; j++)
   {
    if(CV_IMAGE_ELEM(t_image,byte,i,j)==1)
    {
     int ap=0;
     int p2 = (i==0)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j);
     int p3 = (i==0 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j+1);
     if (p2==0 && p3==1)
     {
      ap++;
     }
     int p4 = (j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i,j+1);
     if(p3==0 && p4==1)
     {
      ap++;
     }
     int p5 = (i==size.height-1 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j+1);
     if(p4==0 && p5==1)
     {
      ap++;
     }
     int p6 = (i==size.height-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j);
     if(p5==0 && p6==1)
     {
      ap++;
     }
     int p7 = (i==size.height-1 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j-1);
     if(p6==0 && p7==1)
     {
      ap++;
     }
     int p8 = (j==0)?0:CV_IMAGE_ELEM(t_image,byte,i,j-1);
     if(p7==0 && p8==1)
     {
      ap++;
     }
     int p9 = (i==0 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i-1,j-1);
     if(p8==0 && p9==1)
     {
      ap++;
     }
     if(p9==0 && p2==1)
     {
      ap++;
     }
     if((p2+p3+p4+p5+p6+p7+p8+p9)>1 && (p2+p3+p4+p5+p6+p7+p8+p9)<7)
     {
      if(ap==1)
      {
       if(p2*p4*p8==0)
       {
        if(p2*p6*p8==0)
        {
         CV_IMAGE_ELEM(dst, byte,i,j)=0;
        }
       }
      }
     }                    
    }

   }

  }            
  cvReleaseImage(&t_image);

}

 //将二值图像转换成灰度，以便显示
  i = 0;j = 0;
  size = cvGetSize(dst);
 for(i=0; i<size.height;  i++)
 {
  for(j=0; j<size.width; j++)
  {
   if(CV_IMAGE_ELEM(dst,uchar,i,j)==1)
   {
    CV_IMAGE_ELEM(dst,uchar,i,j) = 255;
   }
   else
   {
    CV_IMAGE_ELEM(dst,uchar,i,j) = 0;
   }
  }
 }

}

//获取图像上的轮廓 坐标 
void GetContoursPoints(IplImage* src , CvMat** LinePoints)
{
	CvMemStorage* storage = cvCreateMemStorage(0);
	CvSeq* contour = 0;
	IplImage* binary_image = cvCreateImage(cvGetSize(src),8,1);
	cvCopy(src,binary_image);

	cvFindContours(binary_image , storage , &contour , sizeof(CvContour) , CV_RETR_CCOMP,CV_CHAIN_APPROX_NONE,cvPoint(0,0) );

//#define SHOWCON
#ifdef SHOWCON
	IplImage* contours;
	contours = cvCreateImage(cvGetSize(src),8,1);
	cvZero(contours);
	cvNamedWindow("con");
#endif 

	int LinesCount = 0;

	for(;contour!=0 ; contour=contour->h_next)
	{
		if(contour->total < 20 )continue;

		LinePoints[LinesCount] = cvCreateMat(contour->total/8,1,CV_32FC2);
		
	
		for(int i=0; i<contour->total/8 ; i++)
		{
	
			CvPoint * pt = (CvPoint*)cvGetSeqElem(contour, i); // 读出第i个点。
			cvSet2D(LinePoints[LinesCount] , i,0,cvScalar(pt->x,src->height - pt->y,0,0));

			//cvSetReal2D(contours , pt->y , pt->x , 255.0);
#ifdef SHOWCON
			CvScalar val = cvGet2D(LinePoints[LinesCount] , i, 0);
			cvSetReal2D(contours , val.val[1] ,val.val[0],255);
		
			cvShowImage("con" ,contours);
			cvWaitKey(0);
#endif

		
		}
		LinesCount++;

	}

#ifdef SHOWCON
	for(int i=0;i<LinesCount;i++)
	{
		for(int y=0;y<LinePoints[i]->rows;y++)
		{
			CvScalar pt = cvGet2D(LinePoints[i] , y, 0);
			cvSetReal2D(contours , pt.val[1] ,pt.val[0],255);
			printf("(%f,%f) ",pt.val[0],pt.val[1]);
		}
	}


	cvShowImage("con" ,contours);
	cvWaitKey(0);
#endif

	cvReleaseMemStorage(&storage);
	cvReleaseImage(&binary_image);

}

// ComputeLinesDis.cpp : Defines the entry point for the console application.
//



#include "LinesDis.h"

int main(int argc, char* argv[])
{
	//对两条直线进行细化
	IplImage *pSrc = NULL,*pDst = NULL,*pTmp = NULL;

	//传入一个灰度图像,从文件中读取图像
	pSrc = cvLoadImage("1.png",CV_LOAD_IMAGE_GRAYSCALE);
	if(!pSrc)
	{
		return 0;
	}

	pTmp = cvCreateImage(cvGetSize(pSrc),pSrc->depth , pSrc->nChannels);
    pDst = cvCreateImage(cvGetSize(pSrc),pSrc->depth,pSrc->nChannels);
	cvZero(pDst);//初始化
	cvThreshold(pSrc,pTmp,128,1,CV_THRESH_BINARY_INV);//做二值处理，将图像转换成0，1
 
	//第一步 对图像中的直线进行细化
	ThinImage(pTmp,pDst,80);


#define SHOWRESULT
#ifdef SHOWRESULT
	cvNamedWindow("src",1);//创建窗口
	cvNamedWindow("dst",1);
	cvShowImage("src",pSrc);
	cvShowImage("dst",pDst);
#endif





	//第二步  提取直线的轮廓坐标
	CvMat*LinesPoints[2];
	LinesPoints[0]=0;LinesPoints[1]=0;
	GetContoursPoints(pDst,LinesPoints);

//#define SHOWCONT
#ifdef SHOWCONT
	IplImage* contours = cvCreateImage(cvGetSize(pDst),8,1);
	cvZero(contours);
	cvNamedWindow("Mcon");
	for(int i=0;i<2;i++)
	{
		for(int y=0;y<LinesPoints[i]->rows;y++)
		{
			CvScalar pt = cvGet2D(LinesPoints[i] , y, 0);
			cvSetReal2D(contours , pt.val[1] ,pt.val[0],255);
			cvShowImage("Mcon" ,contours);
		}
	}


	cvWaitKey(0);
#endif


	//第三步 对轮廓上的坐标进行直线拟合 计算直线方程 By = Ax + b
	float params[4] , k[2] , b[2] , A , B;
	cvFitLine(LinesPoints[0] , CV_DIST_L2,1,0.001,0.001,params);
	k[0] = params[1]/params[0];
	b[0] = params[3] - k[0]*params[2];
	A    = k[0];
	B    = 1;

	printf("y=%f*x+%f \n",k[0]*180.0/3.1415,b[0]);

	cvFitLine(LinesPoints[1] , CV_DIST_L2,1,0.001,0.001,params);
	k[1] = params[1]/params[0];
	b[1] = params[3] - k[0]*params[2];

	printf("y=%f*x+%f \n",k[1]*180.0/3.1415,b[1]);

	//第四部  计算两条直线之间的距离 公式是: |b1-b0| / sqrt(A*A + B*B)
	float 	dis = abs(b[1]-b[0])/sqrt(A*A + B*B);

	printf("dis is %f \n" , dis); 



	// 释放内存
    cvReleaseImage(&pSrc);
	cvReleaseImage(&pDst);
	cvReleaseImage(&pTmp);

	if(LinesPoints[0])
	cvReleaseMat(&LinesPoints[0]);
	
	if(LinesPoints[1]);
	cvReleaseMat(&LinesPoints[1]);
	cvWaitKey(0);

	return 0;
}