Relicate real camera settings for UE virtual production

for a virtual production set we are working on I need to replicate some custom camera settings.
But I am wondering what the right settings are.

I.e. we are shooting with three different cameras.
A gopro Hero 9 with a sensor size of 6,17 x 4,55mm and a fixed f-stop of 2.8, (it has though a wide lense, a linear lense etc. but always the same sensor size.
A Canon Eos 5D (newest) with cine lenses
and a Canon EOS 7D MK2 with prime 35mm as well as a zoom 70-200 mm

Here is the question:
What values do I set in UE? The equivalent to a full frame?
i.e. the Gopro Hero 9 would be a sensor of 6,17mm * 4,55mm, F-stop 2.38 (equivalent of F-15) and a 3mm lens (equivalent is i think 15mm).

But the result does not match real-footage. ;D (not even 16:9 aspect ratio.

What would you do? Does anyone has a good guide / tutorial on this?

Thanks a lot!

PS: I’ll keep searching and crawling the board and net for answers

The GoPro is a fisheye so the default lens setups won’t work.
Ideally, you’d provide post-processing that applied lens calibrated distortions to the image.
Supposedly will be an easier process in 4.27

Hey, yes and know ;D It is luckily doing the post on board already. I get a nice smooth linear image.
Though I am having trouble calculating the equivalent sensor size for UE.

like Hero 9 is using the sony IMX 677 sensor specs of the image sensor with a format of 9,28 x 8,55mm
effectively it is using less pixel then the available once of course. It could do 5599 x 4223 px but for the 4K 60fps we are shooting in it is 3840 x 2160 in resolution.

I need to do some match and move and blend the virtual space over the footage. But to make that work all the settings need to be as close as it gets to the real one.

I am really stuck by now. I “just” need an equivalent sensor size for the gopro 19mm digital lense @3840*2160 px image resolution. Probably it is just too late in time right now and i can not see wood past the trees in front of me.

So you’re shooting grids with the cameras and recreating that grid test in UE with your camera settings?
Are you taking into account the nodal point of each setup?
Are you using OpenCV or something to generate lens parameters based on checkerboards and then applying those in Nuke or other compositing software?

Are you using the CineCamera? It has a few more real-camera-like parameters to adjust over the regular CameraActor, although still not a lens simulation system.

Hey @scottunreal

no, :wink:

I just need the scene to match the real footage as close as possible. In almost any 3D software you can just simply set a resolution or sensor size combined with focal point distance or lense specs. (in UE you can do that too, just a bit limited).

@jwatte @scottunreal
What you normally do is just take the lens’s focal distance and the sensor size and boom you go everything you need. BUT the go-pro is just using digital lenses. It physically just has one sensor size and one lense. The rest ist computational. The stock lense is a fish-eye lense which needs to be un-distorted. And the sensor has a crazy true 5K resolution but to do all the computation and have the high fps it shoots at a virtual sensor size / resolution of 4K (3840*2160 px).

Now normally that would be easy. I just take the lense focal point and recalculate the dimensions of the sensor. BUT its somehow not working here right. I must overlook something. As unreal is using ONLY the sensor size to direct everything. (which is technically the correct, physical, logical way to do).

I hope to find a workaround. When I find it I will post it here as well.