Fig. 4

An illustrated example of \(3 \textrm{D}\) shifted windows. The input size \(H^{\prime } \times W^{\prime } \times D^{\prime }\) is \(8 \times 8 \times 8\), and the 3D window size \(M \times M \times M\) is \(4 \times 4 \times 4\). As layer l adopts regular window partitioning, the number of windows in layer l is \(2 \times 2 \times 2=8 .\) For layer \(l+1\), as the windows are shifted by \(\left( \frac{S_{H}}{2}, \frac{S_{W}}{2}, \frac{S_{D}}{2}\right) =(2,2,2)\) tokens, the number of windows becomes \(3 \times 3 \times 3=27\). Though the number of windows is increased, the efficient batch computation in [19] for the shifted configuration can be followed, such that the final number of windows for computation is still 8