3DHOP x-ray tool 2.0

Hi everyone,

Last May I released the x-ray tool, a small extension for 3DHOP I had developed during the 3D documentation project of the Similaun mummy (Ötzi). It loads two aligned meshes of the same subject, an outer surface and an inner structure, and lets you make the outer one semi-transparent, so that what is inside becomes visible without moving the camera. In the first version the effect was a simple on/off toggle.

I have just published version 2.0, which turns that toggle into a real-time control. A new x-ray intensity slider, at the bottom centre of the viewer, regulates the transparency of the outer shell continuously, from an almost invisible shell to a dense "ghost"; the value used on the Ötzi project, 0.9, is still the default, and the toolbar button remains as an on/off shortcut. Version 2.0 also adds the standard 3DHOP measure tool, calibrated in millimetres.

To make the tool easier to try, the repository now includes a live demo on GitHub Pages: lucaarcteam.github.io/3dhop_x-ray_extension/x-ray.html. The demo subject is a left hand with two rings, a homage to Wilhelm Röntgen's first radiograph (Hand mit Ringen, 1895): you can orbit the model, switch the x-ray on and drag the slider to see the bones appear through the skin in real time.

Below, you can see the live demo of the x-ray tool 2.0.

The x-ray tool 2.0 live demo: the Röntgen hand, with the x-ray slider and the skeleton visible through the skin.

Everything runs in the browser with static files, with no server-side code. As in the first version, the 3DHOP core is left untouched: all the extension logic lives in the x-ray.html page and uses the native transparency API, so the tool keeps working with upstream 3DHOP. The code is released under GPL-3.0-or-later, while the demo models come from the open Z-Anatomy atlas (CC BY-SA 4.0).

You can find the source code, the live demo and the release notes on GitHub. The tool was born within the study published in Heritage 2026.

I hope you find this useful. Have a nice day!