A Topological Picture Book, Rendered
This interactive page renders classic mathematical surfaces—like Boy's surface and Morin's surface—as hand-hatched pen-and-ink drawings, complete with contour lines, dashed hidden lines, and paper halos. The strokes are generated algorithmically using principal curvature directions and a broad-nib pen model, with coherent hand wobble and ink bleeding effects. The page includes a detailed description of the techniques and references to the original literature, such as Francis's 'A Topological Picture Book' and Hertzmann's work on non-photorealistic rendering.
The drawing is made of strokes, not pixels.
- e-infinityspace
This is my project — thanks for the interest. I just made it more mobile / small device friendly.
The app is primarily based on ideas of Hertzmann and Zorin in [this paper](https://cims.nyu.edu/gcl/papers/hertzmann2000iss.pdf), using directions of principal curvature for hatching directions.
- sevensor
I was an undergraduate student of George's many years ago and it's an absolute delight to see these renderings. He used to doodle them on any available surface -- blackboards, notebook paper, napkins, what have you -- often with a fountain pen. He was also big into using computers for visualization and had a number of programs that ran in the CAVE.
- sheept
In addition to making the sidebar dismissable on small screens, it'd be nice to add touch-action: none to the canvas so rotating the object doesn't get interpreted as a scroll on touchscreens.
Right now, at least in Android Chrome, dragging to rotate only works briefly before it's interrupted.