Broadcast DE 2024.3, Unreal, single workstation. All Cameras (1 V CAM, 2 T CAM) are genlocked and fed directly into the system as 2160p30 over a BMD Decklink 8K. Rendering in 2160p30, output downscaled to 1080p30. Allow virtuals off in all cameras (keying in Aximmetry). Keying is set up with clean plates on all cameras. Green box evenly lit with 9pcs 400W RGBWW LED panels and 4pcs 60W LED fill/top lights.
Not using billboards on our tracked cameras (yet) as a) we do not have virtual objects in front of the talent and b) the keying quality seems to suffer a lot from doing that...
However this causes a visible artifact every time we switch from a V CAM to a T CAM. Only in this direction, not vice versa and also not when switching between T CAMs or V CAMs. See video and screenshot:
The first frame after the cut is always keyed incompletely, there are parts in the top of the picture missing. The frames after this are fine.
Turning the billboard on on the T CAMs fixes *that* issue. However with "Render to depth" enabled as per default we get these weird glowing seams that we can't seem to get rid of:
Turning "Render to depth" off with the billboard still enabled gets rid of the seams, but the keying quality suffers. Especially the green spill seems to becomes a lot worse.
So what can we do here?
Hi Stefan,
If I am correct, the issue where the billboard is cropped for one frame when switching between mixed cameras will be fixed in the next version.Until then, I think you might be able to resolve it by using billboards and turning off the Look At Camera option in the Billboard panel.
When ‘Render to Depth’ is turned off, the billboard is actually placed twice in the Unreal level—first in the depth (which will be picked up by reflections and other effects). Unfortunately, the billboard rendered for depth will also be visible to the actual camera. Normally, you would not notice this, as it should always be fully behind the actual billboard that is not rendered to depth.
The unusual glow you see is likely caused by Depth of Field (Focus) being applied to the billboard rendered for depth. To fix this, you should ensure that the billboard is always in focus.
In V Cam (Virtual Camera), you can adjust the focus as described here: https://aximmetry.com/learn/virtual-production-workflow/starting-with-aximmetry/aximmetry-composer/camera-mover-mouse-control/#focus
In T Cam (Tracked Camera), make sure the talent remains in focus with your studio camera (if you have focus tracking) or override the tracked focus in Aximmetry. In the next version of Aximmetry, there will be a parameter in the INPUTS to override only the focus value per INPUT. Until then, you can achieve this with some additional logic in the Flow Editor; if needed, I can describe how to do so.
Regarding the green spill, it appears the above Depth of Field effect is simply blurring away the spill. This can occur if the keyed talent has transparent parts. You should make sure the Low and High Cut settings make the talent opaque in Matte Monitor Mode: https://aximmetry.com/learn/virtual-production-workflow/green-screen-production/keying/keying/#low-cut
Otherwise, try adjusting the Despill parameters of the keyer: https://aximmetry.com/learn/virtual-production-workflow/green-screen-production/keying/keying/#despill-strength
Alternatively, you might be able to hide the green spill using Light Wrap, afterall it is similar to what the Depth of Field's blur artifact did:
To use Light Wrap, the Use Billboards must be enabled.
Warmest regards,