For Mutual Learning 是用的Local distances做的N*N的距离矩阵吗？ about alignedreid-re-production-pytorch

[huanghoujing]

多谢您的关注！

这里global和local的矩阵都可以拿来做mutual learning，可以选择性用哪一个，参见这里和这里。

[Phoebe-star]

hi , do you know what is the zero gradient in the paper (3) ?

and your code in the train_ml.py , line 519

Global Distance Mutual Loss (L2 Loss)

  gdm_loss = 0
  if (cfg.num_models > 1) and (cfg.gdm_loss_weight > 0):
    for j in range(cfg.num_models):
      if j != i:
        gdm_loss += torch.sum(torch.pow(
          g_dist_mat - TVT(g_dist_mat_list[j]).detach(), 2))
    gdm_loss /= 1. * (cfg.num_models - 1) * len(ims) * len(ims)

I can't understand " g_dist_mat" and " TVT(g_dist_mat_list[j]).detach()" .
if the "TVT(g_dist_mat_list[j]).detach() " is the zero gradient , than what do you do ?
thanks

[huanghoujing]

Hi, yes, detach is my understanding of zero gradient in the paper. When .detach() is applied to a Variable, it returns a new Variable that is a leaf node and stops gradients through itself.

[Phoebe-star]

could you explain again with 中文? what is the zero gradient ?
thanks you

[huanghoujing]

我理解的zero gradient的意思是梯度传到那里就不往下传了，所以这里可以用Variable的detach method来实现。

[Phoebe-star]

this is mean the mutual loss don't backpropagation, only metric loss do backpropagation

[michuanhaohao]

@Phoebe-star 你好，我是论文一作，zero grad是指把这个变量当常数来看，原版论文使用了megvii的框架，Pytorch没有这个operator，Pytorch可以用detach来实现