Field notes on the build · Generative Assets
A crust that keeps the time — assembled here the way it assembles on the rock, one wandering particle at a time.
Concept
USNEA is a fictional lichenometry field studio: they read time off lichen crusts, and build instruments that turn slow growth into a reading. The page has one job — make the geologic patience of colonisation legible in under a minute, without lying about it. The crust on the boulder is a real diffusion-limited aggregation, not a video or a texture, so every reload draws a different rock.
Palette
Pulled straight from a saxicolous crust in raking light: dark wet stone, the sage of a settled thallus, and the sulphur flash of fresh growth at the margin. Nothing decorative — each colour is a thing on the rock.
Following the collection's hardest-won lesson, sulphur is a mark colour, not a text colour on busy fields. Body copy runs in bone; small labels in a muted sage-grey; sulphur is spent only on lines, the growing edge, and single accents.
Type
Typographic bravery lives in two places: the USNEA wordmark, set in Newsreader Light at up to 12.5rem and revealed letter-by-letter on a slow rotate; and the age numeral in the slow-clock section, a single Newsreader figure the height of the viewport that counts up as the crust fills.
Technique — the signature element
The whole visual is two stacked canvases and no libraries. A boulder silhouette is generated from a union of six perturbed ellipses (a seeded RNG keeps the outline stable) and rasterised into a mask grid at 4 px cells. The granite body is shaded per masked cell against a raking light, then grained with speckle.
Growth is true DLA. Three spores are seeded in the lower crevices. Each frame a handful of walkers launch on a short ring around the frontier — the recently-fixed cells — then random-walk across the mask until they graze an occupied neighbour, at which point they fix permanently and become a new edge. Because only the exposed edge catches wanderers, the crust reaches outward in fingers and interiors fill last — the characteristic DLA dendrite, which is the same rule that grows coral, frost and mineral trees.
Two layers keep it cheap: fixed particles are painted once onto a persistent canvas (sage sprites, with a 4.5% chance of a sulphur apothecium fleck — a second-read detail), so the crust never redraws. A transparent top canvas clears each frame to carry only the live things: the sulphur flash at each fresh fixing, the faint bone trail of the particle currently wandering, and the ring pulse when you seed. A stick budget that eases as coverage rises is what compresses decades into a minute, then slows to a geologic crawl. Click bare granite and a new colony starts from your point.
Discipline for the collection floor: DPR capped at 2, canvases sized to the viewport with a debounced rebuild, the rAF loop paused on document.hidden with a clamped delta on resume, and prefers-reduced-motion pre-grows the aggregation to ~42% synchronously and paints one settled frame — never a blank.
Iteration log