 Furthermore, BIH are also binary trees just like kd-trees (and in fact their superset, BSP trees).Finally, BIH are axis-aligned as are its ancestors.Although a more general non-axis-aligned implementation of the BIH should be possible (similar to the BSP-tree, which uses unaligned planes), it would almost certainly be less desirable due to decreased numerical stability and an increase in the complexity of ray traversal.