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The measurement library

Facial measurements, explained.

A line is useful when you know what its endpoints mean. Learn how a photograph becomes a measurement, and where the interpretation stops.

An angle describes the relationship between lines. A ratio compares two distances. Neither is a complete assessment of a face. This library explains TrueMax's constructions before discussing what a score might mean.

Two ways to describe geometry On the left, an angle opens between two rays sharing point B. On the right, a short distance and a longer distance form a ratio. These are abstract examples, not ideal faces. On small screens, the two distances are labelled X and Y in the key below. ANGLERATIOABCopening at BDistance ADistance BA ÷ B ABCXY
A, C
The endpoints of the angle's two rays.
B
The shared corner where the angle is measured.
X, Y
Two distances. Their ratio is X ÷ Y.
Original schematic, not to scale. An angle uses a shared vertex; a ratio divides one measured distance by another. The units and endpoints must match before comparing two tools.
Gonial angleFind the visible jaw corner, understand the hinge estimate, and separate a surface angle from skeletal anatomy. Canthal tiltRead the line between the eye corners, understand the sign, and see why head position matters. Side-profile analysisSee what the thirteen landmarks contribute, what needs reviewing, and what a side photo cannot establish. From measurements to a scoreUnderstand reference fit, model scores and why two apps can disagree about the same image.

Three checks before interpreting a number

  1. Placement: are the marked points on the intended visible features? A correctly drawn line between incorrect points still produces an incorrect measurement.
  2. Construction: which points and baseline are used? “Jaw angle” can refer to different constructions. A frontal outline, a side-photo surface angle and an X-ray measurement are not interchangeable.
  3. Reference: what does the comparison actually represent? Agreement with a model range is different from a model score and different again from demonstrated accuracy.

How to read the units

Degrees describe an angle. A ratio has no physical unit when both lengths come from the same coordinate system. A percentage may express one distance relative to a reference length, not a population percentile. TrueMax's side lip-to-E-line values, for example, are normalized by nose-bridge-to-chin-bottom distance. They are not millimetres.

A worked ratio makes the distinction concrete: if the measured nose width is 42 image units and mouth width is 60, their ratio is 42 ÷ 60 = 0.70. Resizing both distances equally leaves 0.70 unchanged. Changing pose or placing either endpoint differently can change it.

What makes a comparison useful?

Use the same image, the same view and the same measurement definition. Record the raw value separately from any rating. When checking change over time, keep the camera setup and expression consistent and inspect the landmarks before interpreting a difference.

More measurements do not automatically mean better evidence

Several measurements can reuse the same points. One misplaced jaw corner can affect multiple results. A long report is not independent confirmation that every number is right, and the number of usable readings depends on the photo.

See the lines behind your result

Start with a front photo; add a side view if you choose. Read the photo guide first, or check plans and scan pricing.

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