Walkable Gaussian Splat: Exploring the Duomo di Lecce with Reactylon and Babylon.js

A 6-minute GoPro video of a Baroque cathedral in southern Italy walks into a local processing pipeline and comes out the other side as a 32 MB navigable Gaussian Splat. No cloud. No paid service. Just COLMAP for camera alignment, Brush for cleanup, and a mass of 732 extracted frames stitched into something you can actually walk through with your arrow keys. Simone De Vittorio's Duomo di Lecce demo lets you drift through the space with smooth cinematic camera movement, and as you approach points of interest, contextual panels float into view with historical and architectural details about the Baroque stonework around you. It feels less like a tech demo and more like a quiet guided tour you stumbled into.

What makes this worth your time technically is the stack underneath. The experience is built with Reactylon, Simone's open-source framework that turns Babylon.js into something you can drive with JSX. It's a custom React renderer, so you get declarative scene composition, lifecycle management, and the component model you already know, but pointed at 3D, AR, and VR instead of divs. The collision system here uses proxy meshes, the camera interpolation is handled cleanly, and the whole thing runs in-browser at a weight that has no business looking this good. The docs alone are worth a visit: over 125 interactive sandboxes, CLI tooling, and starter templates for Vite, Next.js, and Astro.

Simone De Vittorio is building Reactylon as a serious bridge between React developers and immersive experiences. Dig into the GitHub repo, poke at the source of the demo, or just wander around a 16th-century Italian cathedral from wherever you happen to be sitting. The fully local splat pipeline is the kind of thing that makes you want to grab your own camera and point it at something old and beautiful.