Constellation88
Draw a star pattern and it names the constellation. A shape-matching engine over all 88 IAU constellations, on web and iOS, matching in under one second.
Built in the gap between graduating and starting at Imperial, for a simple reason: I love constellations, and I wanted something that could recognize one from a rough sketch. The algorithm was the means, not the point.
You draw a shape and it matches it to one of the 88 IAU constellations. The pipeline normalizes the drawn coordinates, runs a two-stage rotational search, then solves point correspondence with the Hungarian algorithm. Star positions come from Stellarium's catalog, projected stereographically into a JSON database, and the whole match runs in under one second. Live at constellation88.com and on the App Store.
Recognize a constellation from a hand-drawn shape, the kind of thing I'd wanted to exist while lying on the field naming stars.
Extracted Stellarium's catalog into stereographic projections and stored it as a JSON database the app could search quickly.
Coordinate normalisation → a two-stage rotational search → the Hungarian algorithm for point correspondence, which is what finally made matches reliable.
Released it as both a website and an iOS app, so the same engine runs whether you're on a laptop or under the sky with a phone.
Live on the web and the App Store, matching a hand-drawn shape to any of the 88 constellations in under one second. The Hungarian algorithm was the piece that finally made the point-to-point correspondence trustworthy.