Smith traces the Bagua's use outward from its role inside the Yijing's own divinatory and philosophical system into Daoist cosmological diagrams, into feng shui compass instruments such as the luopan, and into folk protective practice, where a Bagua mirror, a small octagonal mirror painted with the eight trigrams, is hung outside a doorway or window understood to face a source of inauspicious influence.
In compass-based feng shui specifically, the Later Heaven sequence maps each of the eight trigrams onto a compass direction and, through that direction, onto an associated family member, natural force and Wu Xing phase, a mapping this atlas records in the Direction entity type rather than repeating here, since the trigram-to-direction correspondences are the same underlying structure viewed from the compass side rather than a second, competing scheme. The Bagua mirror's protective use, hanging a small mirror bearing the eight trigrams to face and deflect an inauspicious external structure or feature, remains common in Chinese and Chinese diaspora domestic and commercial practice today, one of the more visibly persistent folk applications of classical Yijing cosmology in ordinary contemporary use rather than only in specialist feng shui practice.