ipdOffset value doesn't work well

[spinningwatt]

The actual IPD used for rendering would be "ipd + ipdOffset". If I increase the ipdOffset value in file steamvr.vrsettings, the image did changed a bit. It seems work. But when I change the ipdOffset to make the final ipd goes to -0.063, steamvr didn't display the left-eye-image in front of the right eye. I should see an inverse image when the ipd is negative, but I didn't.

So, does the ipdOffset work as a real offset? It seems just like a scale to the virtual world, and it's not a real IPD offset.

[spinningwatt]

To make the difference noticeable, I even set the ipdOffset to an exaggerated value like 10.0 or 20.0. These extreme values should make the two eye cameras too far to stay in a small room, but I can still get a normal view of SteamVR Home, with the scene just in a different perspective than the 0.063 ipd.