I wrote some relatively simple semantic segmentation code that may be of use to you: https://github.com/Kaixhin/FCN-semantic-segmentation 24
However, I too haven’t managed to get great results - I do get OK results though, and never blank outputs. Do you have a link to the Theano implementation that matches your PyTorch one? The closer they are, the easier it will be to pick up any discrepancies.