Question

I’ve got coordinates of one pixel of my image (for example int i,j;), how can I write them into a vector like the following one?

std::vector<KeyPoint> keypoint_object;

Answer 1

From the documentation, I see there is a constructor for KeyPoint that allows insertion of your indices. However it requires an additional parameter size, and I don’t know what you need that to be.

However, the general idea would be this:

keypoint_object.push_back(KeyPoint(i,j,0));

Here, i and j are implicitly cast to float (I assume that is what you require) and the third argument is 0 (as it’s mandatory) — you probably want a more sensible argument here.