Palpebral fissure height : length
Vertical eye opening at the pupil divided by horizontal eye length, averaged over both eyes.
How to read it
the eyes are relatively narrow vertically for their length ("almond" or hooded configuration). Note this value depends heavily on gaze, fatigue and expression at the moment of capture.
vertical eye opening is typical for the reference group.
the eyes are relatively round/open for their length. As with the low case, this is state-dependent — brow raise and surprise inflate it.
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 0.349 ± 0.043 | 0.348 ± 0.042 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 0.343 ± 0.047 | 0.344 ± 0.046 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 0.349 ± 0.044 | 0.35 ± 0.044 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 0.348 ± 0.043 | 0.349 ± 0.043 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 0.353 ± 0.044 | 0.354 ± 0.044 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 0.353 ± 0.044 | 0.353 ± 0.044 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 0.349 ± 0.047 | 0.35 ± 0.047 | 3922 | Unweighted pool of the six groups above prov. |
Where these numbers come from
Transcribed from the cited anthropometric literature; SDs of ratios are propagated conservatively (independence assumed). Entries marked prov. await line-by-line audit against the primary tables — see the norm provenance note.
Why every value has an error bar
Every value Canthion reports carries a 1σ uncertainty propagated from MediaPipe Face Mesh's published accuracy (3.96% of inter-ocular distance mean absolute error per landmark, Kartynnik 2019). For a typical 300 px inter-pupil photo that is ≈12 px per landmark, which is why small ratios and angles get wide intervals. A number without an interval is a number pretending to be more precise than it is.
References
- Farkas, Katic & Forrest (2005). International Anthropometric Study of Facial Morphology in Various Ethnic Groups/Races. J Craniofac Surg 16(4):615–646. doi.org/10.1097/01.SCS.0000171847.58031.9E
- Kartynnik, Ablavatski, Grishchenko & Grundmann (2019). Real-time Facial Surface Geometry from Monocular Video on Mobile GPUs. arXiv:1907.06724. arxiv.org/abs/1907.06724
Related: how bone-level measurements are taken from a photo · methodology · all insights