A computer-implemented method of encoding a point cloud to generate a bitstream of compressed point cloud data, the point cloud being defined in a tree structure having a plurality of nodes having parent-child relationships and that represent the geometry of a volumetric space recursively split into sub-volumes and containing the points of the point cloud, wherein occupancy of sub-volumes of a volume is indicated using a bit sequence, wherein each bit of the bit sequence indicates the occupancy of a respective sub-volume of the volume in a pre-defined scan order within the volume, such that the respective sub-volume is that sub-volume of the volume that corresponds to said bit, and wherein a volume has a plurality of neighbouring volumes, the method comprising: for each of a plurality of current nodes, each current node associated with a current volume of said volumes split into sub-volumes, and wherein each sub-volume corresponds to a child node of the current node, determining the bit sequence indicating the occupancy of the sub-volumes of the current volume; and for at least one bit in the bit sequence of the current volume, determining, based on occupancy data for sub-volumes of at least one neighbouring volume of the current volume, a sub-volume neighbour configuration that depends on an occupancy pattern of a group of sub-volumes of the at least one neighbouring volume that neighbour that sub-volume of the current volume that corresponds to the bit in the bit sequence; selecting a probability for use in entropy encoding of the bit in the bit sequence, wherein the selecting is based at least in part on the sub-volume neighbour configuration; and entropy encoding the bit in the bit sequence based on the selected probability using a binary entropy encoder to produce encoded data for the bitstream. for each of a plurality of current nodes, each current node associated with a current volume of said volumes split into sub-volumes, and wherein each sub-volume corresponds to a child node of the current node, determining the bit sequence indicating the occupancy of the sub-volumes of the current volume; and for at least one bit in the bit sequence of the current volume, determining, based on occupancy data for sub-volumes of at least one neighbouring volume of the current volume, a sub-volume neighbour configuration that depends on an occupancy pattern of a group of sub-volumes of the at least one neighbouring volume that neighbour that sub-volume of the current volume that corresponds to the bit in the bit sequence; selecting a probability for use in entropy encoding of the bit in the bit sequence, wherein the selecting is based at least in part on the sub-volume neighbour configuration; and entropy encoding the bit in the bit sequence based on the selected probability using a binary entropy encoder to produce encoded data for the bitstream. determining, based on occupancy data for sub-volumes of at least one neighbouring volume of the current volume, a sub-volume neighbour configuration that depends on an occupancy pattern of a group of sub-volumes of the at least one neighbouring volume that neighbour that sub-volume of the current volume that corresponds to the bit in the bit sequence; selecting a probability for use in entropy encoding of the bit in the bit sequence, wherein the selecting is based at least in part on the sub-volume neighbour configuration; and entropy encoding the bit in the bit sequence based on the selected probability using a binary entropy encoder to produce encoded data for the bitstream.