This readme needs work but it should at least be informative.
This application is a tool to generate a 3D preview and 2D laser-cutting template of custom selections of stars and constellations projected onto a regular polyhedron of your choice. Stars data comes from actual astrometric catalogues and includes accurate positions and enables filtering based on apparent brightness.
Projecting onto a regular polyhedron (a 3D shape in which all faces are the same) means we can easily "un-fold" the projected results into a 2D template for cutting and then re-fold that into a physical 3D shape.
The final result is effectively a lamp shade, allowing a light source (ideally very small, bright, and omni-directional) to project individual points of light onto the walls and ceiling of a room.
The tool will start up with default selections for the target shape, minimum brightness level, and constellations. Any of these can be modified to and the results will be re-projected in the preview pane automatically.
Note: the full catalogue includes over 98k stars. Not only can it take quite a while to project the entire selection, but most of them are very faint stars (meaning you likely wouldn't recognize them) and they would be bunched very close together. The latter can be especially problematic due to overlapping cuts: without manual (tedious!) cleanup you could end up with a ring of connected stars causing a section of the projector to be unintentionally cut out. Think of the island in a stencil of the letter "O".
The list of constellations is pre-filtered to only count those that are "interesting". The full list maps out 88 constellations and you might be surprised how many of them look like a simple line. My filter requires that a constellation includes at least one star that connects to at least 3 other stars.
You can visualize what it's like to unfold the 3D shape by clicking on it. It looks neat but doesn't actually serve much of a purpose.
The easiest way to turn this into something real is to work with a local laser cutting service and use some kind of heavy paper (I've had success with bristol board). I have made a few attempts using a consumer-grade vinyl cutter but still need to find the right mix of paper weight, blade settings, and polygon size. In either case, the final output of this tool is a vector template that will determine cutting and scoring lines for the polyhedron itself as well as geometry like star shapes and constellation lines.
Among the star/constellation customizations on the left you have options to determine the size of the output template based on dimensions of your material, the desired real-life radius of your projector, or edge length of each polygon face. You can also choose whether to keep the unfolded net intact or to split it up into separate SVG files for individual polygons. The latter gives you the opportunity to arrange them more efficiently or to maximize the size of your output in an otherwise limited paper or cutter size. It also means you have more tabs to align and glue together afterwards: for the time being you are responsible for figuring out how things fit together.
The star catalogue is a compilation of the Hippcarcos,Yale Bright Star Catalog, and Gliese Catalog of Nearby Stars collected and organized in the HYG Database.
The list of constellations was painstakingly compiled by Daniel Plemmons for a really cool VR Planetarium.