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?
Applied to a blog, angkorwatification is a sort of textual equivalent of rewilding. You have a base layer of traditional blog posts that is essentially complete in the sense of having created, over time, an idea space with a clear identity, and a more or less deliberately conceived architecture to it. And you have a secondary organic growth layer that is patiently but relentlessly rewilding the first, inorganic one. That second layer also emerges from the mind of the blogger of course, but does so via surrender to brain entropy rather than via writerly intentions disciplining the flow of words.