请查看以下代码
#include <opencv2/core/core.hpp>#include <opencv2/imgproc/imgproc.hpp>#include <opencv2/highgui/highgui.hpp>#include <iostream>#include <vector>using namespace cv;using namespace std;void houghTransform(int,void*);Mat image,lines,dst,cdst;int thresh;const char* imageWindow = "Image Window";int main(){ image = imread("DSC01894.jpg"); //将dst图像转换为灰度图 if(image.data!=0) { cv::Canny(image,dst,50,200,3); cv::cvtColor(dst,cdst,CV_GRAY2BGR); cv::createTrackbar("Threshold",imageWindow,&thresh,255,houghTransform); houghTransform(0,0); } else { cout << "无法读取图像" << endl; } namedWindow("Image"); imshow("Image",image); waitKey(0);}void houghTransform(int, void *){ vector<Vec4i>lines; cv::HoughLinesP(dst,lines,1,CV_PI/180,thresh,50,10); for(size_t i=0;i<lines.size();i++) { Vec4i l = lines[i]; cv::line(cdst,Point(l[0],l[1]),Point(l[2],l[3]),Scalar(0,0,255),3,CV_AA); } imshow(imageWindow,cdst);}运行时，我遇到了运行时错误，
其中一个参数的值超出了范围。应该是在
cv::HoughLinesP(dst,lines,1,CV_PI/180,thresh,50,10); 或
cv::line(cdst,Point(l[0],l[1]),Point(l[2],l[3]),Scalar(0,0,255),3,CV_AA);为什么会这样？
回答：
我遇到了这个异常，内容是
OpenCV Error: One of arguments' values is out of range (rho, theta and threshold must be positive) in unknown function, file C:\slave\builds\WinInstallerMegaPac k\src\opencv\modules\imgproc\src\hough.cpp, line 718这个异常出现在以下代码中
if( rho <= 0 || theta <= 0 || threshold <= 0 ) CV_Error( CV_StsOutOfRange, "rho, theta and threshold must be positive" );在 cvHoughLines2() 中，该函数由 cv::HoughLinesP() 调用。
传递给 HoughLinesP() 的参数是：
rho=1theta=0.0174533threshold=0问题在于：阈值（threshold）不允许为0。
