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sniklaus / pytorch-pwc

a reimplementation of PWC-Net in PyTorch that matches the official Caffe version
GNU General Public License v3.0
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what is the range of optical flow value in an image? #50

Closed Pixie8888 closed 3 years ago

Pixie8888 commented 3 years ago

Hi, Thanks for this work! I use this pwcnet to estimate optical flow. I have a question regarding the value range of optical flow. Is it range from (-w+1, w-1) (-h+1, h-1)? If I want to normalise optical flow to (-1,1), should I follow this: optical_flow[0,:,:] = optical_flow[0,:,:]/ (w-1) optical_flow[1,:,:] = optical_flow[1,:,:]/ (h-1)? (w and h is the image size. optical_flow_shape = (2, h, w))

sniklaus commented 3 years ago

The neural network is not constrained to any range. If you want the estimated optical flow to be within the range of [-1, 1] you will have to divide by w and h respectively.