# How to implement soft-IoU loss?

I am trying to implement soft-mIoU loss for semantic segmentation as per the following equation. but loss is very low and I am not able to find the wrong step in the implementation.

``````def to_one_hot(tensor,nClasses):

n,h,w = tensor.size()
one_hot = torch.zeros(n,nClasses,h,w).scatter_(1,tensor.view(n,1,h,w),1)
return one_hot

class mIoULoss(nn.Module):
def __init__(self, weight=None, size_average=True, n_classes=2):
super(mIoULoss, self).__init__()
self.classes = n_classes

def forward(self, inputs, target_oneHot):
# inputs => N x Classes x H x W
# target_oneHot => N x Classes x H x W

N = inputs.size()

# predicted probabilities for each pixel along channel
inputs = F.softmax(inputs,dim=1)

# Numerator Product
inter = inputs * target_oneHot
## Sum over all pixels N x C x H x W => N x C
inter = inter.view(N,self.classes,-1).sum(2)

#Denominator
union= inputs + target_oneHot - (inputs*target_oneHot)
## Sum over all pixels N x C x H x W => N x C
union = union.view(N,self.classes,-1).sum(2)

loss = inter/union

## Return average loss over classes and batch
return loss.mean()
``````

Can any one help me?
Thanks

2 Likes

Hi, I am wondering whether have you solved the problem?

Yes, there was a minor bug. Written code is correct except the return statement; in which returned loss need to be negative:

``````return -loss.mean()
``````

Thanks

Hello !
I’m confused by this loss, becaose ti seems that if the pixel value more corect, the loss become larger, and the value equal to label ,the loss would be 1?

Sorry, I didn’t notice your last comment !

hi, what is name of this paper?

I guess this paper. https://www.cs.umanitoba.ca/~ywang/papers/isvc16.pdf

I think this paper.
DeepRoadMapper: Extracting Road Topology from Aerial Images
According to paper: Optimizing Intersection-Over-Union in Deep Neural Networks for Image Segmentation, the loss should be `1 - soft_IOU`.