[cloud-oak]

The thing is, 3D to 2D projections work well because that's how our eyes work in the first place, so we can intuitively understand a projected image on the screen.

When projecting 4D to 2D, weird things start happening. Instead of a ray, each pixel now represents a plane in 4D space. So even while it can be done mathematically, the brain is just overwhelmed by what happens when you e.g. rotate the projection