Xuan Kong Da Gua (玄空大卦) is the most precise of the classical Feng Shui systems because it maps the 64 I Ching hexagrams onto compass directions at single-degree resolution. Where Flying Stars works at 45° sector granularity, XKDG works at ~5.6° per hexagram — a property audit at this level is dramatically more sensitive to the actual structure than a generic Feng Shui sweep.
What an XKDG property audit produces
An XKDG audit identifies four hexagrams for any property: the sitting hexagram (the hexagram of the back wall direction), the facing hexagram (the hexagram of the front), and the bedroom + work-desk hexagrams within the structure. Each hexagram is read against the occupants' birth-year hexagrams for compatibility. A property whose sitting hexagram clashes with the breadwinner's birth hexagram is fightable; a deeply harmonious match is rare and worth seeking out before purchase.
The 64-hexagram compass map
The 360° compass is divided into 64 hexagrams of 5.625° each. Each hexagram is one of the 64 I Ching hexagrams (Qian, Kun, Tun, Meng, Xu, Song, Shi, Bi... through to Wei Ji). A precise compass reading of the back wall (sitting direction) is taken with a Lou Pan (Chinese geomantic compass) or a calibrated Western compass with magnetic-north correction. The reading produces a hexagram name; that hexagram is the property's sitting hexagram for the current Period (Period 9, 2024–2043).
Reading hexagrams against occupants
Each occupant has their own birth-year hexagram. The sitting hexagram is compared to it through three levels: (1) trigram compatibility (upper trigram of one hexagram against lower trigram of the other), (2) elemental relationship (the five-element interaction between the two hexagrams), and (3) "host-guest" dynamics (which hexagram dominates). Strong matches: the sitting hexagram supports the occupant's birth hexagram. Strong mismatches: the sitting hexagram drains or controls the occupant. Most properties are mixed — some occupants benefit, others struggle.