How to set IPD?

"Mark" wrote:

"geekmaster" wrote:
The eye strain is from tantential distortion causing the vertical misalignment of parts of the two images while trying to view them stereoscopically. This happens when viewing from an IPD that does not go through the optical axis (sweet spot) of the lens. Mismatched eye/lens IPD also causes increased chromatic aberration. Both of these things can be corrected in software with a better pre-warp shader that does not leave out the tangential distortion and chromatic aberration correction portions of the "Brown's model" lens distortion correction formula.

I have an OpenGL shader that performs the full Brown's model correction, but I have not tested it yet. I plan to use it on my Raspberry Pi (if I do not replace it with a cached displacement map first).

Is it just Unity that doesn't have this "Brown's model" correction, or does the Oculus SDK lack this as well?

My IPD is 55. I don't have my Rift yet, so I don't know what it will be like to use it, but I'd like to find out how to best compensate for the IPD mismatch.

They use a subset of the Brown's model that leaves out the tangential distortion correction and the chromatic aberration correction, relying on only radial distortion correction (optimized for 64mm IPD) at this time.

However, the main page of this website has an announcement that an "IPD calibration tool" will be provided in the future, so perhaps that tool generates the missing lens distortion correction coefficients, and the SDK will be updated to supply the missing terms to use them.

But even with that software supplying improved lens distortion correction, only the shape and color of displayed objects will be improved. Any focusing errors from incorrect physical lens position for your IPD will remain. It will still be a good idea to supply optional replacement lens cups with various IPD selections (or better, adjustable IPD). And replacement cups should allow lens focus adjustments too, by changing their distance from the screen.

In fact, with mechanically adjustable lenses, radial distortion correction alone would have been sufficient (as is commonly done for other adjustable lens applications).