fix segmentation demo

[williamFalcon]

@akshaykvnit @Borda

 ERROR collecting pl_examples/full_examples/semantic_segmentation/semseg.py

 No module named 'torchvision.models.segmentation'
oops, looks like this test fails. Need to fix asap

[akshaykulkarni07]

@williamFalcon
According to this page, it does exist. Not sure why it fails.

[williamFalcon]

probably has to do with the version of torchvision which i noticed isn't being checked or anything

[akshaykulkarni07]

@williamFalcon
According to this page, segmentation models were introduced in version 0.3 of torchvision. So, I think the tests might be using older versions (for backwards compatibility maybe?)

What I can do is add a custom implementation of U-Net (popular architecture) and replace the torchvision model. But even that'll take a few hours because I have some work right now.

[williamFalcon]

@akshaykvnit yes please. That would be ideal. This is breaking the core tests, so we'll have to roll this back otherwise.

Thanks!

[Borda]

@williamFalcon major question is what torchvision version do you want to support, in past we had there torchvision>=0.4

[akshaykulkarni07]

@williamFalcon major question is what torchvision version do you want to support, in past we had there torchvision>=0.4

I would also suggest keeping torchvision>=0.3 at least because a lot of object detection and segmentation models were introduced in 0.3. These are very good architectures which will be good for examples, instead of using custom models.

[Borda]

Note that this package is not dependent on torchvision any more, just some tests and examples...