why stop gradients on upsample

[shoutOutYangJie]

o1, o2, o3, o4, o5 = s1.detach(), s2.detach(), s3.detach(), s4.detach(), s5.detach() o11, o21, o31, o41, o51 = s11.detach(), s21.detach(), s31.detach(), s41.detach(), s51.detach()
why do you use detach here? you mean that VGG's parameter is freezen?

[pkuCactus]

No, we don't stop the gradient of upsample. we just stop the gradient to the previous predictions which we suppose the prediction is the proper edge that layer predict.

[yxchng]

@pkuCactus Is it necessary to detach()? What will happen if we do not detach()?