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?
Why? Because if you do, in time you will begin to see a difference.
The buses that move out of Helsinki stay on the same line but only for a while, maybe a kilometer or two. Then they begin to separate, each number heading off to its own unique destination. Bus 33 suddenly goes north, bus 19 southwest.
...It’s the separation that makes all the difference, and once you start to see that difference in your work from the work you so admire (that’s why you chose that platform after all), it’s time to look for your breakthrough.
Suddenly your work starts to get noticed. Now you are working more on your own, making more of the difference between your work and what influenced it.