One of the perennial problems that we come across in a variety of contexts, including CNC artwork and producing artwork for the Egg-Bot, is the difficulty of creating good-quality toolpaths– i.e., vector artwork representing halftones –when starting from image files.
One of the finest solutions that we’ve ever come across is Adrian Secord’s algorithm, which uses an iterative relaxation process to optimize a weighted Voronoi diagram, producing a set of points (stipples) that can closely approach the appearance of a traditional stipple drawing.
Another important technique is “TSP art,” where the image is represented by a single continuous path. You can generate a path like this by connecting all of the dots in a stipple diagram. Designing a route that visits each dot exactly once is an example of the famous Travelling Salesman Problem (or TSP). From the standpoint of toolpaths (for the Egg bot and most other CNC machines), a “TSP” path is even nicer than stipples, because little or no time is spent raising and lowering the tool.
Today we’re releasing a new program, StippleGen, which can generate stipple diagrams from images, using Secord’s algorithm. StippleGen saves its files as editable, Eggbot-ready Inkscape SVG files, which can in turn be opened by other vector graphics programs, or re-saved as PDF files for use in other contexts. It can also generate a TSP path from the stippled image, and either save that path as an SVG file or simply use that path as the order of plotting for the stipple diagram.