There’s a NMS-related question that seems controversial. I’ll try my best not to break the honour code with my description:
- The quiz states that the parameters for NMS include a probability ρ, used for discarding boxes with probability ≤ ρ, and a IoU value of ν for determining if two boxes overlap.
- In the image, you can observe two objects that belong to the same class κ: object A has been enclosed in two different bounding boxes with probabilty > ρ whereas object B is “contained” by only one bounding box with probability < ρ.
- The quiz asks if NMS will only keep objects A’s bounding box with the highest probability. This is not an exact transcript of the question, of course.
- Apparently, the correct answer is “True. Only one of the boxes for an object of class κ is kept because the score S (i.e. probability) is higher, and also because it has a larger bounding box”. Again, not an exact transcript.
I’m convinced that the correct answer is, indeed, “True”, but I don’t agree with the justifications. I believe object B’s bounding box is “immediately” discarded because its probability is less than ρ. In addition, and even though both of object A’s bounding boxes have probability > ρ, only the one with the highest value is kept as a consequence of these boxes having an IoU larger than ν.
I guess my questions are:
- What does NMS have to do with the size of a bounding box?
- Are my arguments correct?
Thanks in advance,