RuntimeError: 1only batches of spatial targets supported (non-empty 3D tensors) but got targets of size
原因:这个原因是因为在使用Crossentropyloss作为损失函数时,output=net(input)的output应该是[batchsize,n_class,height,weight],而label则是[batchsize,height,weight],label是单通道灰度图;BCELoss与CrossEntropyLoss都是用于分类问题。BCELoss是CrossEntropyLo