Question

I am trying to create a CvMat data structure using cvMat() in OpenCV.

The last parameter of cvMat() expects a void* to the data.

My data is stored in the following data structure

vector<vector<CvPoint2D32f>> data;

I expected

data.at(0)

to work as the last parameter, but the compiler says that it can not convert to void*.

What path should I be taking now ?

Create an array from vectors ? That would waste a lot of time/memory.

Answer 1

data.at(0) has vector<CvPoint2D32f> type, but you need pointer to the first element of that vector. Try:

 &(data.at(0).at(0))

Also keep in mind, that vector<vector<CvPoint2D32f>> is not a two dimensional array of CvPoint2D32f. It is more like “vector of references” to one dimensional arrays.