How to store multiple descriptors, from different images, in a vector of vectors in C++ and OpenCV?

I'm using OpenCV to evaluate some algorithms for face recognition, at the moment I'm using HoG ( Histogram of Oriented Gradients)

我正在使用OpenCV来评估一些人脸识别算法，目前我正在使用HoG（方向梯度直方图）

I wish to store descriptors, from several images, in a vector, for later comparison.

我希望将几个图像中的描述符存储在一个向量中，以便以后进行比较。

For each image it stores X descriptors in a vector of floats usually initialized like this:

对于每个图像，它将X描述符存储在通常初始化为浮动的向量中，如下所示：

vector <float> descriptors;

So, in order to store many, I thought the initialization would be something like this:

所以，为了存储很多，我认为初始化将是这样的：

vector <vector <float> > descriptors;

Although the program compiles ok, it stops at hog.compute without any warning or error.

虽然程序编译正常，但它在hog.compute处停止，没有任何警告或错误。

for (i = 0; i < images.size(); i++){

    hog.compute(images[i], descriptors[i], Size(16,16), Size(4,4), locs);

}

Any tip or suggestion?

任何提示或建议？

Thank you in advance!

先谢谢你！

1 个解决方案

#1

You should allocate enough space for descriptors before calling it. There's only a empty container by vector <vector <float> > descriptors;, it will crash if you trying to access its elements, i.e. descriptors[0], because descriptors.size()==0 currently.

在调用之前，您应该为描述符分配足够的空间。 vector > descriptors;只有一个空容器，如果你试图访问它的元素，即描述符[0]，它会崩溃，因为descriptors.size（）== 0当前。

You can simply change

你可以简单地改变

vector <vector <float> > descriptors;

to

至

vector <vector <float> > descriptors(images.size());

or

要么

vector <vector <float> > descriptors;
descriptors.resize(images.size());