Create beautiful boards with Gerbolyze

+ Today, there is an increasingly large crowd of people who do artistic circuit board designs. People who fuse + the roles of engineer and artist. Unitl today, circuit board design tools mostly ignore this use case and + present a multitude of obstacles for such use. Gerbolyze finally solves this problem and presents an + integrated solution for artistic PCB design that is compatible with real designer's workflows on one side + and with real electronic design automation software on the other side. +

A printed
+ circuit board showing a surrealist manga-style drawing of a woman sitting atop several traffic
+ lights. The woman's hair looks golden from the circuit board's gold copper finish. The
+ background is blue and white with scales of gray emulated through a halftone technique like it
+ is used in newspapers. — + **An artistic PCB design** +
+ This design was created from a digital artwork in a raster image file after circuit board + manufacturer PCBWay offered me some free boards. The artwork was pre-processed using a raster + graphics tool: It was split into layers for the different colors. Then, its color components were + adjusted for brightness and contrast and finally passed through a raster-based halftone filter. The + resulting file was then converted into circuit board manufacturing files using Gerbolyze. +
+

+ Thirty years ago, the world of printed circuit board design was revolutionized by the introduction of + computer aided design tools. These tools enabled extremely complex designs through automation features + like autorouting and through automatic design rule checking to weed out human error. While the first + such tools were still very limited, their capabilites quickly grew and a few years after their + introduction modern electronics design without computers was already unthinkable. +

+ Today, circuit board design programs can look back on a rich history and have accumulated a healty + amount of expert knowledge in their design. Despite their difficult economic niche, even free + software design tools have grown to become usable for advanced designs. However, all modern + circuit board design tools are severely lacking in one area: That of artistic design. Many + design assumptions are hard-wired deep into their design: Traces should be at 45° angles. Silkscreen is + one opaque color. etc. These design assumptions lead to these tools being in the way more often + than not for the increasing crowd of designers who try to create art with them. +

+ Gerbolyze solves this problem. Gerbolyze interfaces with circuit board design tools such as Altium or Kicad + on one side through standard Gerber files. It interfaces with vector graphics editors such as inkscape on + the other side through Scaleable Vector Graphics (SVG) files. By fusing both, it yields a powerful + environment for artistic circuit board design. +

Gerbolyze Algorithm Overview

+ Gerbolyze has two major components. The first is the gerbolyze executable itself, which orchestrates the + process of fusing SVG and Gerber files. The second is svg-flatten, a tool encapsulating all of the + heavy-duty computer graphics code. The gerbolyze executable is a python script for readability, while the + geometry backend is a C++ binary for performance. +

+ In the beginning of the fusing process, the orchestrator figures out what semantic layers such as silkscreen + or copper the tool's input files correspond to. The assigned layers are then processed one by one. For each + layer, the tool first checks the input SVG file for any content. If there is none on this layer, the layer + file is directly copied to the output. If ther is some, this SVG content is passed through the geometry + backend to convert it to Gerber code. The resulting Gerber code is then read and added on top of the input + file's gerber code. The result is written to the output. +

The Computer Geometry of Scaleable Vector Graphics

+ The heavy lifting during this process is done by the geometry backend. While its job seems simple at first, + it is surprisingly stretching the state of the art in both academic research and technical implementations + of computer graphics. In its core the problem is that while SVG and Gerber are both essentially vector + graphics formats, both have very different conceptions of their drawing models: They differ significantly in + what happens when one of the input file's vectors is drawn. +

+ SVG is little more than a highly standardized description of the basic operations provided by the modern 2D + graphics interfaces such as Qt, Cairo or Skia that are built-in to all operating systems. Drawing + paths that are described by the vector coördinates of points along them is the most basic of these + operations. SVG also includes support for a surprising number of decidedly raster operations such + as masking but, operating on grayscales, these are less relevant for the type of design one would create + when targeting circuit board production processes. +

+ Similar to SVG, the Gerber file format also targets a type of graphics programming interface. Only instead + of that of operating systems 2D graphics APIs of the 90ies and 2000s, the Gerber format was created as a way + to encapsulate commands for photoplotters, computer-controlled machines that physically move a light source + across a photo-sensitive material. Gerber's concept of "aptertures" goes back to mechanical photoplotters + having magazines of stencils of different shapes and sizes that could be swapped into the path of light + during the plotting process. +

+ Like SVG has its paths, the Gerber format has polygons. Polygons were added to the format to ease the + description of irregularly-shaped areas: Previously, these would have to be drawn by overlaying thousands of + thin lines, described one by one in the Gerber file. Using a Polygon, one only needs to describe the shape's + outline as a series of points and the photoplotter will fill in the rest. +

Transforming Vectors into Vectors

+ The crux in converting from SVG to Gerber lies here, in the conversion of paths. While in both a path or + polygon is described by its outline, which is described by points, there are significant differences in the + limitations both place on these outlines. In SVG an outline can consist of several types of segments: + besides basic straight lines, multiple types of parametrized curves including cubic bezier curves are + possible. An SVG path's outline can self-intersect (cross over itself). The path can also have holes, + additional parts that are inside the outline. +

+ Gerber, on the other hand, has a much more limited view of what a polygon is. In gerber, a polygon is + something bounded by straight line segments, that cannot touch except under very particular circumstances, + and holes are simply not supported. Converting from SVG's flexible model of a path to Gerber's very + limited model of a polygon while preserving the fidelity of the input data is the true challenge here. As an + aside, a fun complication one will encounter when embarking on this endeavour is that most programs that + display Gerber files use modern graphics libraries in the backend. In these programs, a valid SVG path + ineptly converted into an illegal gerber polygon may still end up looking alright since these programs + usually just pass through the gerber's input data to the underlying graphics layer without validation—and + that graphics layer is the one from SVG. +

Styles and Strokes

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Gerbolyze Image Vectorization