I totally agree, though I think it would be interesting to measure/study the amount of interference from an overlay needed to cause sickness. Imagine you have a

I totally agree, though I think it would be interesting to measure/study the amount of interference from an overlay needed to cause sickness. Imagine you have a simplified model which shows the countour of perspective lines and significant objects of a scene, how many of these lines can then be interrupted, overlayed or rerouted before you introduce too much noise in the visual perception and get sick. It would differ from person to person, but I'm pretty sure it's some kind of normal distribution. I don't think there's been many public studies trying to quantify this.