Virtual table in a tracked green box

Hi everyone,

we run a pretty standard 8x8x3 meters green box here, 1 VCAM (BMD Micro 4K) and 2 TCAM (BMD URSA Broadcast G2). Sets in Unreal, Single Broadcast DE workstation, currently on 2025.1 but will probably have to upgrade to 2025.3 for this as explained later.

The studio works great as an empty green box with just a photorealistic background room and the odd virtual object like a wall with a TV on a stand or a mobile LED wall. But now a big client wants to incorporate an actual virtual furniture piece into it for a talkshow-style production. The general idea was something like this:

Virtual table in a tracked green box

The background isn't really an issue, the Unreal designers we work with are pretty good at making stuff like this look realistic. Plus it's obvious that the glass surface won't work either on the table or the floor, this will have to be some opaque material with maybe some reflective pieces in carefully selected areas. Kind of like this:

Virtual table in a tracked green box


Now, the hard part is putting it into practice. We aren't Unreal Designers, and while the Unreal Designers we work with are really good at making photorealistic rooms they have little actual broadcast experience. So we did some experiments:

https://www.dropbox.com/scl/fi/f87zzitpfs59bhgt3vmd1/PGM_UHD_0232.mp4?rlkey=9eugywnfs1jum8kc7ygh5tsql&st=tbgvy95f&dl=0

https://www.dropbox.com/scl/fi/fbrh82o4a5a5mau7d8gt3/PGM_UHD_0233.mp4?rlkey=qp6rrcc1immre149r5ske40i4&st=ppg3uiis&dl=0

The keying is deliberately way off so the contours of the green table stay visible. With a clean plate it vanishes completely while objects on top of it are keyed in well, so that part works.

There are two things here where we are a bit stuck now:

First of all it seems to be really difficult to get the dimensions of the virtual "table" and the green placeholder to match up. They are designed to be the same diameter and the position can be adjusted with a blueprint transformation, but it seems impossible to get more than one edge at a time to match well enough. What are some tricks to do this better in Unreal, and how do you go about hiding the inevitable imperfections?

Secondly Billboard placement. It seems like with a round table the best way of doing this is having the billboard effectively halve the table so at least from the standard +-45 degree camera angles onto talent sitting or standing in a half circle around the table the table is always in front of any visible body parts. On the tracked cameras this will obviously require using a billboard with a horizontal section, hence the upgrade to 2025.03. 

But what about the VCAM? There is no horizontal section on the Billboard there (yet...).

Third, what rendering settings should we use in Aximmetry to make this look realistic? Currently we do not allow virtuals (Keying in Aximmetry only) and also do not render shadows of real objects as it looks better if we just go with the real shadows on the green box floor. 

Any Ideas? Are we missing something completely here?


   Stefan Reck

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