Why 42 classes?

Question

Why 42 classes?

acaelles97 opened this issue 2 years ago · comments

First of all, congratulations on the nice work!
I wanted to ask why the number of classes is 42 if YT-Vis only has 40 classes. One extra class is used for the background but what about the other one?

I also don't understand why you include the background class if you use focal loss. Original Deformable DeTR focal loss implementation ignores background because it is basically given by the sigmoid probabilities for all the classes being < 0.5.

Thanks a lot for your help!

Junfeng Wu · Answer 1 · Fri Mar 25 2022 12:58:15 GMT+0800 (China Standard Time)

Hi, thanks for your attention.
Yes, 40 classes is enough for focal loss. Since we keep the background and vanishing object classes for experimentation, so here is 42.
Actually this can be changed to 40 completely, sorry for the misleading.

Adrià Caelles · Answer 2 · Wed Mar 30 2022 19:24:00 GMT+0800 (China Standard Time)

Thanks for your answer
Does the performance stay the same without these 2 extra classes?

Junfeng Wu · Answer 3 · Sat May 14 2022 22:13:54 GMT+0800 (China Standard Time)

Yes, this has no impact on performance.