What's the aim of "* 20.0" after two upscale operation in the class "Upconv"?

[EmiliaCarbon]

class Upconv(torch.nn.Module):
    def forward(self, tenOne, tenTwo, objInput):
        objOutput = {}

        tenInput = objInput['conv6']
        objOutput['flow6'] = self.netSixOut(tenInput)
        tenInput = torch.cat([objInput['conv5'], self.netFivNext(tenInput), self.netSixUp(objOutput['flow6'])],
                             1)
        objOutput['flow5'] = self.netFivOut(tenInput)
        tenInput = torch.cat([objInput['conv4'], self.netFouNext(tenInput), self.netFivUp(objOutput['flow5'])],
                             1)
        objOutput['flow4'] = self.netFouOut(tenInput)
        tenInput = torch.cat([objInput['conv3'], self.netThrNext(tenInput), self.netFouUp(objOutput['flow4'])],
                             1)
        objOutput['flow3'] = self.netThrOut(tenInput)
        tenInput = torch.cat([objInput['conv2'], self.netTwoNext(tenInput), self.netThrUp(objOutput['flow3'])],
                             1)
        objOutput['flow2'] = self.netTwoOut(tenInput)

        return self.netUpscale(self.netUpscale(objOutput['flow2'])) * 20.0         # * 20.0 here

What is the aim of this multiplication? My guess is to enlarge the output of the network, because the network should output the absolute size of the offset. Is my guess right?

[sniklaus]

I ported the official TensorFlow model, which multiplies by 20 as follows.

https://github.com/simonmeister/UnFlow/blob/bf0c09972dca0bc139c5ed39f25cc25c86f79037/src/e2eflow/core/flownet.py#L48

For additional questions, you might want to direct your question at the authors of UnFlow.