compute this matching otherwise you would have no clue which boxes to come which predictions to compare to which other predictions so let's look at this architecture a bit more in detail as we said you have this what they call the backbone which is a convolutional neural network and with that you put in some positional encodings now I already said the you should look at the these features right here as just smaller feature versions of the image but they still have some image nature then they are flattened so once they are put in