I believe Occupancy Networks is using octrees for surface extraction (i.e. construct a voxel grid given your SDF). See figure 2 in the Occupancy Networks Paper.
On the other-hand, octrees are used in this paper to store variable resolution feature volumes (i.e. to improve the representation of the SDF). See figure 3 in Neural Geometric Detail Paper.
On the other-hand, octrees are used in this paper to store variable resolution feature volumes (i.e. to improve the representation of the SDF). See figure 3 in Neural Geometric Detail Paper.