Concatenating feaute maps spatially


Possibly v silly question.
If I have to features maps of identical size, say (32,64,10,10), I would like to concatenate them so as to get
an output of size (32,64,20,20).
Usually I have seen concatenation of feature maps along the channel axis, but I think it is being done it the way described above for the model I am trying to implement.


Do you mean “2”. Something is wrong in your description.

2 feature maps of size (32, 64, 10, 10) = 2 x 32 x 64 x 10 x 10 elements = 409600 elements

1 output of size (32, 64, 20, 20) = 32 x 64 x 20 x 20 elements = 819200 (double the previous)

So any way of concatenating 2 inputs with that size won’t give you output of desired size (unless you’re adding elements from somewhere else)

Did you mean concatenating 4 inputs?

Yup. My bad. I figured it out. I blame it on working too late at night :wink: