bounds of each node, 6 per node: min x, y, z then max x, y, z, quantized relative to the tile bounds
per node: the poly index for a leaf node, or the negated escape index (nodes to skip) for an internal node
the quantisation factor for the bounding volume tree
bounds of each node, 6 per node: min x, y, z then max x, y, z, quantized relative to the tile bounds