Technique · Fields
Light ribbons
Long-exposure light trails: bundles of glowing strands that sweep, braid and fan out across a deep violet ground.
Light ribbons is a field drawn for every pixel by the graphics chip. Every piece on Synapse Drip is made from a recipe that layers techniques like this one, and you can change any of it in the Studio.
Good to know
- Light painting began as a photographic game: the exposure stays open while a person moves a small light through the dark, and the picture records the whole path at once.
- Photographers now make light trails of traffic by shooting a motorway at night with a shutter open for ten or twenty seconds.
- Fibre-optic lamps make rainbow strands because each fibre is lit by a rotating colour wheel; the fibres carry the light along their length and glow at the ends.
- A long-exposure photograph keeps the shutter open for seconds, so moving lights, car headlights or a sparkler waved by hand, leave continuous trails.
- Gjon Mili photographed Pablo Picasso drawing in the air with a small light in 1949, a picture series known as light drawings.
The mathematics
- A strand is a glowing curve: the light at distance d from it is exp(-d^2 / w^2) for the core plus a wider exp(-d / 4w) for the halo; here 16 strands per ribbon are added, so where several overlap the sum climbs toward white.
- Each ribbon follows y = A (sin(kx + p) + 0.55 sin(1.7 kx + 1.4 p) + ...), a sum of sines with unrelated frequencies, so it never repeats visibly; the slope of the curve is used to turn vertical distance into true distance from the curve.
- The fold comes from warping the plane before the ribbons are measured: bending the space the curve lives in lets a function that can only give one y per x loop back on itself.
In art
- The Futurist painters of the 1910s tried to show speed by drawing the path of a moving thing as a smear of repeated lines, as in Giacomo Balla's Dynamism of a Dog on a Leash (1912).
- Neon and light art, from Dan Flavin's fluorescent tubes of the 1960s onward, treat light itself as the material.
More ways to use it
Related techniques
Nebula and stars · Liquid · Droplets · Network · Terrain and maps · Neuron · Order to chaos · Fractal tree