Last year we described an experiment run at a concert stadium. We put an integral imaging–based volumetric 3D display onto a 40 m × 30 m water screen at Incheon and Busan's Asiad Main Stadiums, during PSY's Summer Swag. That post ended with a prospect: that this technology could be useful well beyond concerts.

A year later we had a chance to test that. On 2 November 2025 the work appeared on Seoul Broadcasting System(SBS)'s Sunday Special Documentary, in an episode titled 'The Power of the Culture Technology Behind K-Content'. For the broadcast we moved the system indoors, replaced the water screen with fog, and stood a haetae on it.

Three things changed at once. Each brought a problem we had not planned for.

What we put in the air, and what it shows

A haetae is the horned guardian beast that sits in stone at the gates of Korean palaces. Over the past year, audiences outside Korea have mostly met this kind of figure through animated K-content.

The one we reconstructed was not made for any particular title. What we wanted to show was what kind of content this display can carry. A system developed for a stadium concert, scaled down and moved onto a different medium, can hold a K-content figure just as well.

The segment took it in that order. What integral imaging is. Where a glasses-free volumetric display is actually useful. And finally, what a guardian beast standing in mid-air looks like when you walk past it. That last question is hard to answer in writing, which is why we were glad of the format.

From water to fog

The Summer Swag tests used water. A water screen is a demanding medium, and we wrote last year about splash and uneven formation. But it is still a surface, and it stays roughly where you put it.

Fog is not a surface at all. It is a cloud of fine droplets held in shape by moving air. Its density changes from moment to moment, and so does its position. A water screen wavers across its face. Fog drifts back and forth in depth.

Integral imaging is particularly sensitive to that second kind of motion. The micro-lens array bends rays so that they meet at a set distance from the screen, and the solid shape a viewer sees is built out of where those rays cross. When the fog moves away from that distance, the image does not simply grow dimmer. The small images formed by each lens begin to disagree with one another, and the sense of depth collapses before the brightness does.

Alignment was therefore the most demanding part of this demonstration: holding the reconstruction distance steady against a medium that never holds still. We ended up fixing that distance to the most stable part of the fog curtain rather than to its geometric centre, and setting the airflow so that this region stayed within the depth range over which the reconstruction holds. The water screen had never asked that of us.

And the camera

The broadcast added one more condition. The result had to survive being filmed.

A camera has one lens in one position. It records a single viewpoint and discards the rest. Someone standing in the room reads the depth as soon as they move their head, but on a flat television screen that same information can arrive as a difference too small for anyone to read as three-dimensional.

Showing a light-field display through a flat medium is not a communication problem to be solved afterwards. What the eye confirms in the laboratory and what a single camera can capture are different conditions, and the second one belongs in the design work from the start.

What comes next

Moving from a stadium to a studio told us that the system holds up across changes of scale and medium. It worked on a large outdoor water screen, on unstable indoor fog, and in front of a camera.

What remains is content and real time. So far, everything we have put in the air was prepared in advance. Add live volumetric capture and transmission, and the screen becomes a window. Bandwidth is still the limiting factor on that side.

Acknowledgements

This work was supported by the Ministry of Culture, Sports and Tourism and the Korea Creative Content Agency. We thank the Summer Swag production team, particularly Park Jaisang (PSY) and CEO Minho Roh of P NATION, and the SBS Sunday Special Documentary team for their interest in the engineering behind the performance.

Watch the segment: [https://www.youtube.com/watch?v=s3aAc8kotOM]