TERRA is a fictional survey house founded 1928. Its site rests on a single argument: a map is not a picture of land, it is a rendering decision. So the hero terrain is generated once — and drawn three ways as you scroll.
The entire landscape lives in one GLSL shader pair. The vertex stage builds the mountain from ridged fractal noise; the fragment stage holds three complete cartographic languages — contour lines, hypsometric tints, hillshade — and a scroll-scrubbed uniform slides the same geometry between them. The page furniture (cartouche, legend, field log) is drawn from the conventions of printed survey sheets.
Lifted from early-20th-century topographic plates: sienna for relief, a dedicated water ink, and the red reserved — as on real sheets — for what the surveyor added by hand.
Cormorant Garamond — the engraver's voice, set in a bordered cartouche with an asterism, the way sheet titles were framed.
Lora — body text with a bookish drafting-room warmth.
Courier Prime — the field-note voice: dates, elevations, instructions.
| Element | How it works |
|---|---|
| Terrain synthesis | Six-octave value-noise fBm, exponent-carved valleys, plus a ridged component (1−|2·fbm−1|) for arêtes — computed per-vertex on a 420×420 plane with finite-difference normals. |
| Contour rendering | Anti-aliased isolines from fract(h/step) sharpened with fwidth — minor lines every 0.12 units, majors every 0.6, exactly like 40 m / 200 m intervals. |
| Three-way morph | One uMode uniform (0→2) blends contour → hypsometric ramp → Lambertian hillshade lit from the cartographic north-west. GSAP ScrollTrigger scrubs it across a 340vh pinned track while the camera glides in. |
| Paper behaviour | Scene fog in sheet-cream fades the far terrain like an unprinted margin; per-fragment hash grain gives tooth. |
| Accessibility | Reduced motion stops rotation and camera drift; the mode card still narrates each rendering. The legend symbols are inline SVG with the section text as context. |
| You do | The page does |
|---|---|
| Scroll the survey track | The mountain re-renders: contour → tint → shade, card and meter following |
| Keep scrolling | The camera descends toward the ridge like a returning aircraft |
| Reach the legend | The sheet's four promised symbols, drawn in their own inks |