I only skimmed the article, but knowing previous solutions, there were attempts to use real subdivision and displacement of the original geometry.
The article does mention this line:
> These subtle adjustments of the 3D space are being applied volumetrically, as can be seen from the way the occlusion paths in the scene are changing. This demonstrates that the FOVO process is not simply ‘warping’ a 2D render in screen space but is applying nonlinear transformations to the entire 3D geometry.
I'm not sure how to interpret this in real terms, but it does seem to suggest at least it might be more than a simple 2d transform
The article does mention this line:
> These subtle adjustments of the 3D space are being applied volumetrically, as can be seen from the way the occlusion paths in the scene are changing. This demonstrates that the FOVO process is not simply ‘warping’ a 2D render in screen space but is applying nonlinear transformations to the entire 3D geometry.
I'm not sure how to interpret this in real terms, but it does seem to suggest at least it might be more than a simple 2d transform