OpenCV的calcOpticalFlowPyrLK抛出异常

问题描述

我一直在尝试用OpenCV形成一个小光流示例。一切工作除了函数调用calcOpticalFlowPyrLK，它打印以下失败的断言在控制台窗口：

我要解析的视频被分成300个图像，标记为caml00000.jpeg，caml00001.jpeg，...，caml00299.jpeg。这是我写的代码：

  #include< cv.h> 
 #includeopencv2 / highgui / highgui.hpp
 
使用命名空间cv; 
 using namespace std; 
 
 int main（int argc，char ** argv）{
 
 char buff [100]; 
 int numFrames = 300; 
 char fileFormat [] =images / caml％05d.jpeg; 
 
 string winname =测试窗口; 
 
 vector< Mat> imgVec（numFrames）; 
 
 auto itrImg = begin（imgVec）; 
 auto itrEnd = end（imgVec）; 
 vector< Point2f>特征： 
 vector< Point2f>特征： 
 
 namedWindow（winname，CV_WINDOW_AUTOSIZE）; 
 int fileNum = 0; 
 while（itrImg！= itrEnd）{
 Mat& imgRef = * itrImg; //从向量迭代器获取此帧的Mat 
 
 //计算文件的名称; 
 sprintf（buff，fileFormat，fileNum）; 
 string fileName = buff; 
 // string fileName =kitty.jpg; //尝试使用静态图片
 cout<< fileName<< endl 
 
 Mat cImage = imread（fileName，CV_LOAD_IMAGE_GRAYSCALE）; 
 cImage.convertTo（imgRef，CV_8U）; //也试过CV_8UC1 
 featuresPrevious = std :: move（featuresCurrent）; 
 goodFeaturesToTrack（imgRef，featuresCurrent，30，0.01，30）; //计算用于下一次迭代的特征
 if（！imgRef.data）{//这从不执行，所以读取文件没有问题
 cout< 文件I / O问题！ << endl 
 getchar（）; 
 return 1; 
} 
 
 if（fileNum> 0）{
 Mat& lastImgRef = *（itrImg-1）; //获取最后一帧的图像
 vector< Point2f> featuresNextPos; 
矢量< char>特征： 
 vector< int>呃; 
 calcOpticalFlowPyrLK（lastImgRef，imgRef，featuresPrevious，featuresNextPos，featuresFound，err）; //问题行
 //绘制连接上一个位置和当前位置的线
 for（size_t i = 0; i< featuresNextPos.size（）; i ++）{
 if（featuresFound [i] ）{
 line（imgRef，featuresPrevious [i]，featuresNextPos [i]，Scalar（0,0,255））; 
} 
} 
} 
 
 imshow（winname，imgRef）; 
 
 waitKey（1000/60）; //不完美，但它会做
 
 ++ itrImg; 
 ++ fileNum; 
} 
 
 waitKey（0）; 
 return 0; 
} 
  

我读到的关于这个异常的唯一原因是垫子是不同的格式，但我已经尝试读取静态图像（见上面关于kitty.jpg的代码），我仍然得到相同的失败的断言。任何想法？

解决方案

更改行 vector< char> featuresFound; 到矢量< uchar> featuresFound; 和向量< int>错误到 Mat err;

我不能解释为什么，如何做。

编辑：
正如@Sluki在注释中说 - err矢量必须存储在浮点精度std :: vector或cv :: Mat。

I have been trying to form a small optical flow example with OpenCV for a while now. Everything works except the function call calcOpticalFlowPyrLK, which prints the following failed assertion in the console window:

The video that I'm parsing is separated into 300 images, labelled as "caml00000.jpeg", "caml00001.jpeg", ..., "caml00299.jpeg". Here is the code I wrote:

#include <cv.h>
#include "opencv2/highgui/highgui.hpp"

using namespace cv;
using namespace std;

int main( int argc, char** argv ){

    char buff[100];
    int numFrames=300;
    char fileFormat[]="images/caml%05d.jpeg";

    string winname="Test Window";

    vector<Mat> imgVec(numFrames);

    auto itrImg=begin(imgVec);
    auto itrEnd=end(imgVec);
    vector<Point2f> featuresPrevious;
    vector<Point2f> featuresCurrent;

    namedWindow( winname, CV_WINDOW_AUTOSIZE );
    int fileNum=0;
    while(itrImg!=itrEnd){
        Mat& imgRef=*itrImg; //get this frame's Mat from the vector iterator

        //Calculate the name of the file;
        sprintf(buff,fileFormat,fileNum);
        string fileName=buff;
        //string fileName="kitty.jpg"; //attempted using a static picture as well
        cout << fileName << endl;

        Mat cImage=imread(fileName, CV_LOAD_IMAGE_GRAYSCALE);
        cImage.convertTo(imgRef, CV_8U); //also tried CV_8UC1
        featuresPrevious=std::move(featuresCurrent);
        goodFeaturesToTrack(imgRef,featuresCurrent,30, 0.01, 30); //calculate the features for use in next iteration
        if(!imgRef.data){ //this never executes, so there isn't a problem reading the files
            cout << "File I/O Problem!" << endl;
            getchar();
            return 1;
        }

        if(fileNum>0){
            Mat& lastImgRef=*(itrImg-1); //get the last frame's image
            vector<Point2f> featuresNextPos;
            vector<char> featuresFound;
            vector<int> err;
            calcOpticalFlowPyrLK(lastImgRef,imgRef,featuresPrevious,featuresNextPos,featuresFound,err); //problem line
            //Draw lines connecting previous position and current position
            for(size_t i=0; i<featuresNextPos.size(); i++){
                if(featuresFound[i]){
                    line(imgRef,featuresPrevious[i],featuresNextPos[i],Scalar(0,0,255));
                }
            }
        }

        imshow(winname, imgRef);

        waitKey(1000/60); //not perfect, but it'll do

        ++itrImg;
        ++fileNum;
    }

    waitKey(0);
    return 0;
}

The only thing I've read about this exception is that it is caused when Mats are in different formats, however I've tried reading a static image (see code above regarding "kitty.jpg") and I still get the same failed assertion. Any ideas?

解决方案

Change line vector<char> featuresFound; to vector<uchar> featuresFound; and vector<int> err; to Mat err;

I can't explain why, but that's how it has to be done.

Edit:As @Sluki said in the comments - err vector has to be stored in floating point precision std::vector or cv::Mat.

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