In optics, a caustic is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light.
A piece of milled plexiglass acting as a projecting lens; via the Computer Graphics and Geometry Lab at the École Polytechnique Fédérale de Lausanne
New milling techniques applied to glass and plexiglass panels could be used to “create windows that are also cryptic projectors, summoning ghostly images from sunlight.”
[Pauly and Bompas] hope that the technique will be used in architectural design, to create windows that mould sunlight and throw images or patterns onto walls or floors,” which, if timed, milled, and manipulated just right, could produce a slowly animated sequence of images being projected by an otherwise empty window during different times of day.
To control the shape of a caustic pattern generated by a specular or refractive surface, we need to solve the inverse problem: how can we change the surface geometry, such that incident light is redirected to produce a desired caustic image?
Super Nintendo games were the flavor of the decade when I was younger, and there’s no better example of building incredible things within comparably meager constraints. Developers on SNES titles were limited to, among other things:
16-bit color.
8 channel stereo output.
Cartridges with storage capacities measured in megabits, not megabytes.
Limited 3D rendering capabilities on select titles which embedded a special chip in the cartridge.
Despite these constraints, game developers cranked out incredible and memorable titles that will endure beyond our lifetimes. Yet, the constraints SNES developers faced were static. You had a single platform with a single set of capabilities. If you could stay within those capabilities and maximize their potential, your game could be played—and adored—by anyone with an SNES console.
PC games, on the other hand, had to be developed within a more flexible set of constraints. I remember one of my first PC games had its range of system requirements displayed on the side of the box:
Have at least a 386 processor—but Pentium is preferred.
Ad Lib or PC speaker supported—but Sound Blaster is best.
Show up to the party with at least 4 megabytes of RAM—but more is better.