The ```Sparse_Conv``` in ```ExampleNet``` Change spatial structure of output of ```Encoder```, so we can't inverse back to input of ```Encoder``` via ```Decoder```, we need to inverse from ```Sparse_Conv.output``` to ```Encoder.output``` via ```Sparse_Conv_Decoder```, then inverse from ```Encoder.output``` to ```Encoder.input``` via ```Decoder```.
### Sparse Add
In sematic segmentation network, we may use conv1x3, 3x1 and 3x3 in a block, but it's impossible to sum result from these layers because regular add requires same indices.