interest points from sliding windows

I use SIFT descriptor like in the first image

and I want to create a bag-of-features statistic at each window position by only considering the interest points within the window like in the second image

Answer 1

[Abhishek Ballaney]

https://in.mathworks.com/help/vision/examples/image-category-classification-using-bag-of-features.html

[N Rh]

I know this example, my objective is not the classification but the SIFT features extraction per sliding window