Unveil the Forehead and Hairline
The calculation of your upper cranial width and longitudinal balance is strictly dependent on hairline visibility. Fringes, stray shadows, or hats introduce analytical ambiguity that directly degenerates metric precision.
Ensure not just the center, but the bilateral temporal crests (temples) are fully exposed.
An asymmetrical hairline is not an issue; an obscured boundary is.
If harsh lighting casts deep volumetric shadows over the boundary, retaking the photo is highly advised.