One Issue about FreeD Lens Calibration in UE

We have one project that we are tracking camera based on UE, but we have encountered some problems in processing shot data and lens calibration in UE.

We can now obtain the Pitch and other data of the real camera through the FreeD protocol. For example, we can successfully obtain and match the Pitch, Yaw, Roll and Aperture of the lens to the virtual camera. But for the variable of Focus Distance, the data we obtained through FreeD protocol is based on the scale value of the real camera’s focus range, which cannot be directly applied to the focus distance of the virtual camera. In other words, we cannot correctly assign the focusing information of the real camera to the virtual camera in UE.

And according to the content in the chapter of lens calibration in the official document, we followed the content for testing, but found that the curve of Focus Distance was not generated in the lens file. Only based on the two initial points entered in the document. Actually, We are still a little puzzled about the specific steps to follow this document, the result we gained also bemused us. We are not so clear, is there something else we should do or can guide us?
We tried to manually make a two-dimensional curve of focus distance and FreeD protocol data, but the accuracy of the curve is unacceptable.

So I wonder if there are some detailed processing methods to match the FreeD protocol data to the real focus distance so that the virtual camera can correctly track the focusing of the real camera?

Thanks in advance!

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