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?
I recently started compiling a list of defunct blogging platforms. It’s been interesting to see how websites die — from domain parking pages to timeouts to blank pages to outdated TLS cipher errors, there are a multitude of different ways.
When buildings are torn down and rebuilt, the ghost of the old building is often visible in the new one — strangely angled walls and rooms, which make sense only in the context of the space as a living organism. On the web, there are no such restrictions: when a website dies, it leaves no sign of its past self behind.
I think a lot about the lifecycle of websites. I’m frustrated by so much of the short-term thinking I see in the world today, and the way we think about websites is a part of that: it’s “normal” for them to just go up in smoke as soon as their authors stop paying attention. People switch platforms and providers and break links without a second thought. It pains me to see people build websites with no feeling of obligation to them — when you put something out into the world, it is your responsibility to care for it.
At the same time, I wonder if this obsession with permanence is misplaced.