Nodal Offset calibration help

Development Cinematics & Media Virtual Production
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Hello, we have been trying for a couple months to setup a Virtual Production studio with a green screen and I’ve gotten to a point where I’m not sure what else to try. I have an Optitrack system that’s tracking the camera and the checkerboard, I’m able to calibrate the distortion of the lens getting a result around 0.13 px but when calibrating the nodal offset point is where I’m stuck. I have tried multiple times and it seems to be always similar where it looks good at some point but then it is completely off (See the video below).

Since we have a tracked camera the idea is to being able to create dynamics shots, but with the current calibration the feet of the actors or the assets starts to drift and it’s noticeable.

Here are some point and tests done:

  • The pivot point of the tracked checkerboard matches the pivot point on the 3D checkerboard.
  • Using UE 5.2.0
  • Tried the nodal offset calibration moving only the checkerboard and capturing around 5 samples
  • Tried the calibration moving only the camera
  • Tried with about 15 samples
  • The nodal offset information is always different with each calibration but it’s never good all around
  • I have an HTC vive and I could try the method with the trackers that I’ve seen online, but having an Optitrack system already set this seems like a few steps backwards

Would greatly appreciate any help or suggestion to try! since I’m almost out of ideas. Maybe this is as good as it can get? Could it be because it’s a wide lens? (I’m using a 16mm)

Thanks in advance!

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I have learnt that in the camera calibration BETA, when setting nodal offset - less is more. I only do two positions. The more i do, the worse it gets.
But in your case it looks like the disrortion is not quite there.
Try it again with 45° angles to the camera aswell.
To check if the distortion is on point, go to “nodal offset” and use the Checkerboard option (not points method) - click on the live view and then “add to nodal offset”. If it looks good, do it over and over again in different positions. This way you can double check if and where exactly the distortion is off.
The calibration tool can be frustrating. I know…

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Thank you! that’s something I haven’t tried yet, I’ll check in a couple days and post here the results.

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How is it looking?

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Any updates?

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Hi Marc!

This project got on pause since we started to work on something else, but I’ll keep you posted when I have new tests. Maybe with all the updates since then now it’ll work better :slight_smile: