Bullet Journal - Digital ink track

title: Bullet Journal - Digital ink track
dated: 2019
author: Szymon Kaliski
related: Deformation

2019-04-12

Inverse-kinematics chain:

Chains with external forces

2019-04-18

Two experiments with combining path simplification (turning hand-drawn points into a set of beziers), and “force propagation” for deformations:

2019-05-09

We decided to look into other methods of path simplification, explored NURBS, and b-splines. Below is a quick prototype that does b-spline fitting

Szymon overall it works pretty good, but it feels best for “smooth” shapes, and has tendency to add little loops and “overdo” sharp edges James The b-spline stuff looks good. I think—as we knew from the beginning—getting this right will require developing a very sophisticated heuristic for determining how adjustments to nodes or control points affects the overall shape. It requires a departure from (more like new layer on top of) the b-spline or bezier math models. An open question for me is whether b-spline (of other more abstract spline systems) allow for more intuitive control of a shape than bezier (which I think of as a specific subclass of b-splines). Key thing being that you need to be able to see, understand, and physically manipulate the control points, and bezier gives you an easy way to visualize the effect of the control points (though has lots of other problems we’ve talked about) whereas the b-spline sometimes can be more intuitive but tend to be hard to understand how they are affecting the curve, and often include “weights” that can’t be easily visualized. Would be super awesome to have someone give us a workshop survey of how the pro-grade 3D tools do this—like the demo reel I posted from that Autodesk car concepting app—so we can see what the existing solutions are. I feel ignorant in this area. Overall I think it was a good experiment and to me validates my desire to do a more serious project in this area. I have as one of the three big research areas I’m concerned with, “what is digital ink?”, and I think this whole line of questions around “how does digital ink behave?” and “how do you manipulate it?” is super key.

2019-05-21

Updated previous code with “smart deformation”