Game Development Reference
In-Depth Information
Where
V
is your game's non-stereo view transform centered between the eyes,
V'
is the fi-
nal stereo correct view transform.
7.3.2 Distortion Correction
The next step is to perform distortion correction to account for the Rift's optics. The lens
used by the Rift magnifies the image, increasing the field of view. It will generate a radi-
al pincushion distortion that will increase the image magnification with distance from the
optical axis, this results in a visible effect in which lines that do not go through the center
of the image are bowed inwards, towards the center of the image.
This distortion can be corrected by applying a mathematically inverse effect, a barrel dis-
tortion.Abarreldistortion,willdecreasemagnification withdistance fromtheopticalaxis,
thevisualeffectisthatofanimagethathasbeenmappedontopofasphere,orabarrel.By
combining the distortions, the pincushion effect is neutralized resulting in straight lines.
Mathematically,barrelandpincushiondistortionsarequadratic,theyincreaseasthesquare
of the distance from the center.
