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?
And what is delight? For me, delight is born from a tool’s intuitiveness. Things just working without much thought or fiddling. Delight is a simple menu system you almost never have to use. Delight is a well-balanced weight on the shoulder, in the hand. Delight is the just-right tension on the aperture ring between stops. Delight is a single battery lasting all day. Delight is being able to knock out a 10,000 iso image and know it'll be usable. Delight is extracting gorgeous details from the cloak of shadows. Delight is firing off a number of shots without having to wait for the buffer to catch up. Delight is constraints, joyfully embraced.