Harmony · Side view · Jaw
Chin Position Relative to the Frankfort Plane
The horizontal position of the chin’s most forward point relative to the nasal root in the oriented photo.
What is measured
The calculation
(Pogonion x − nasion x) × photo scale
Side view / Measurement guide
Follow the measurement
Select a label to focus on its line. Select again to show all measurements.
In these guides, nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point. Frankfort refers to the direction from the ear-opening landmark to the lower orbital landmark.
Why it matters
This compares the chin with an upper-face reference. It adds directional information to profile angles, but depends on where the nasal root sits as well as the chin.
- Negative: the chin point lies behind the nasal root.
- Positive: it lies in front of the nasal root, in the oriented profile.
Where the idea comes from
FaceIQ adaptation
Clinical profile analysis uses head references to compare projection. FaceIQ uses horizontal coordinates in the oriented image; the formula does not independently rotate the points into a Frankfort coordinate system. [1]
A worked example
A chin 15 units behind the nasal root at 0.2 estimated mm per unit reads −3 mm.
Example values explain the calculation. They are not a target range and are not measurements of the schematic above.
Research & further reading
The sources below explain the history or related evidence. FaceIQ’s score weights and reference ranges are model settings; these papers do not collectively validate the scoring system.
[1] Holdaway · 1984
A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part IIExplains how lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance.