Portalgraph Brings VTuber Dancing to Your Desk in 3D Without Glasses
Extended Reality
5 minutes read
A video has been making the rounds on social media, featuring the famous hololive VTuber, Marine Houshou, dancing to "Innocent Maiden" inside a transparent little box on a laptop. This isn't just a flat video; it moves with the viewer's perspective, creating a 3D spatial effect, like a futuristic mini-theater. It’s reminiscent of the Gatebox we talked about earlier, a holographic projection device developed to enable being in the same spatial environment with the virtual idol Hatsune Miku. Check it out here.
After a bit of digging, I found out that this video uses a technology called Portalgraph. As the name suggests, Portalgraph acts like a portal to a 3D world, even though it's technically flat. You don't need special displays or 3D glasses. Just pair it with tracking devices like the VIVE Tracker, and the virtual character seems to exist in the real world. Sounds intriguing, right? Let’s dive into this technological marvel.
How Does Portalgraph Differ from Holography?
When people see such displays, they often think of "holography." While both create a 3D illusion, their underlying technologies are entirely different.
Holography uses the principles of light interference and diffraction to create a true 3D light field image in the air or a specific medium. This allows you to see different sides of an object from various angles without the need to track the viewer's position. However, holography typically requires special optical equipment and a highly controlled projection environment, making it costly and technically demanding. It's mostly used in exhibitions and commercial spaces.
Portalgraph, on the other hand, is based on "perspective tracking," adjusting the screen in real-time to create a similar 3D illusion. The 3D effect comes from the screen's alignment with the viewer's head position, not actual light field projection. In other words, Portalgraph offers a more DIY-friendly, affordable, and interactive experience.
Almost no blind spots with naked-eye 3D. (Source: Portalgraph)
In practice, these display setups usually use two to three screens (like a base and a back) to form an L-shaped or box-like small display structure. The "box" here isn't a transparent acrylic box or projection film but is made of LCD screens—like a laptop's main screen paired with an external monitor to form an L-shaped device. Portalgraph generates corresponding perspective images on each screen, so when you move your head, it feels like you're looking into a little world with depth. That's why it seems like the character is dancing inside the box, but it's actually the system dynamically rendering the corresponding angle based on your position, creating a visual illusion.
To achieve this "perspective-following" 3D illusion, the key is linking it to the user's head position. This is where the VIVE Tracker comes in handy. By attaching the tracker to the user's head, it can send real-time head position data back to the Unity system. Portalgraph uses this data to dynamically change the virtual camera's angle and focus. Compared to using a webcam for facial tracking, the VIVE Tracker offers higher precision and stability.
If you want to DIY, developers offer detailed tutorials. (Source: Portalgraph)
Want to Try DIY?
Portalgraph is open-source, so if you're interested, you can download the package on GitHub. The official documentation provides complete installation and operation instructions. Whether you're a VTuber fan, creator, or just curious about 3D displays, you can try building your own "virtual box."
