> If we can't fool viewers, we haven't achieved realism. And the only way to check is to put some nature videos side by side with our simulations and ask "Which one is real?"
Your proposed experiment cannot tell us whether current techniques fall short.
The experiment can only demonstrate when we are there, after the fact. It cannot demonstrate that we won't get there on our current heading, and it can't even demonstrate that we're not already there.
I realize it's the intended point of your test, that doesn't mean it will work. Your test cannot do what you claim just because you want it to.
Read the article about argument from ignorance. For your test to work, you'd have to guarantee it had the best CG that's possible. You can't guarantee that. You can never prove we're not already there because no matter what CG you make for the test, someone else can always try harder, take more time, use better artists and bigger computers, spend more money. Abscence of evidence is not evidence of abscence.
Your logic is faulty, your argument is suffering from a fallacy. You can speculate that your idea of realism isn't possible yet, but no test can prove it.
I think you are making a classic fallacy of 'argument from ignorance'. https://en.wikipedia.org/wiki/Argument_from_ignorance
Your proposed experiment cannot tell us whether current techniques fall short.
The experiment can only demonstrate when we are there, after the fact. It cannot demonstrate that we won't get there on our current heading, and it can't even demonstrate that we're not already there.