Claude Opus 5.5 and Blender turn one illustration into anime hair

The project's most useful lesson is a measurement problem, not a modeling trick. The author built an inspection suite — face-rule violations, self-intersection inside a strand, contact with body and clothes — and treated all-zero as a pass. The long-hair prototype cleared that bar while looking like a slitted curtain, which pushed the pass condition itself to change from "the checks pass" to "it does not look like a curtain," tracked through thickness and layer overlap.

A second round of fixes came from looking at individual strands rather than whole sections. Splitting 29 strands into six types revealed that 21 of 29 still bent while thick at the tip, and that the median width 30 mm from the tip was 29.5 mm. The rebuilt version brought that to 0 of 29 and 12.1 mm, though the share of gaps showing the body through the tips rose from .091 to .153.

The tooling has a cost the author states plainly: texture-drawn lines are cheaper in time and token cost than editing hair structure and improve the look, but taste varies. Wave expression and sideways volume remain unfinished, with costume and animation work prioritized instead.