Stroke, corner radius and fill have to be a system
Aliases: icon parameters · stroke weight · corner radius · icon family
What it is
A set reads as a set not because the subjects match, but because the same drawing parameters are executed again and again: stroke, cap, corner radius, interior padding, filled or not. Scatter the parameters and even handsome individuals look, in a row, like letters picked from mixed sizes and mixed typefaces. Consistency is a production constraint, not a later pass of "nudge until it feels close".
Why it happens
People scan side-by-side glyphs as members of one class at one level. The scan does not start with subject matter; it starts with contour statistics — thick or thin, square or round, hollow or solid. Jitter in those statistics is registered as "these are not the same kind of thing": some look like titles, some like asides, some like broken pixels. A system nails the statistics so subject matter is allowed to vary. Without one, the instinct is to fix whether a single drawing "looks like the thing", while the fight is actually 1.5 px versus 2 px strokes, and 2 px versus 4 px corners.
Where it stops holding
- Two intentional parameter sets — one for navigation, one for in-content marks — are legal if their venues are split. They must not alternate inside one toolbar.
- Brand illustration can ignore the table. The moment it is scaled to 24 px and used as an icon, it has to join the table, or it becomes a crushed picture in the bar.
- Dark-background strokes often need an optical fattening. That is compensation inside the same system, not a second system.
- Outline mixed with filled being read as "selected" is a different failure. This one is whether parameters were written down as one executable set.
Applying it
- Before drawing the second glyph, write the table: stroke, cap, corner, grid, minimum interior gap, default fill. Every later glyph may only take values from that table.
- Review a new icon inside the existing 24 px strip, not enlarged in the middle of the artboard. An enlarged draft hides a half-pixel stroke miss.
- How to check: export the whole set as a same-size sprite sheet and blur until subjects vanish. If some glyphs still read as thicker, rounder, or more solid, the parameters never became a system.