Comment by jms55 | Hacker News Reader

Comment by jms55 | Hacker News Reader

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> performance is only good if you have a current-generation GPU that cost at least $1k

That's why I said games aren't currently designed with only pathtracing in mind, but in 3-5 years with faster hardware and better algorithms, we'll probably start to see it be more widespread. That's typically how graphics usually develop; something that's only for high end GPUs eventually becomes accessible to everyone. SSAO used to be considered extremely demanding, and now it's accessible to even the weakest phone GPU with good enough quality.

Again the fact that it's feasible at all, even if it requires a $1000 GPU, is amazing! 5 years ago real time path tracing would've been seen as impossible.

> The way it went for CP2077 makes your "70% usable" claim seem like quite an exaggeration

Based on the raw frame timing numbers and temporal stability, I don't think it is. RT GI is currently usually around ~4ms, which is at the upper edge of usable. However the temporal stability is usually the bigger issue - at current ray counts, with current algorithms, either noise or slow response times is an inevitable tradeoff. Hence, 70% usable. But with another few years of improvements, we'll probably get to the point where we can get it down to ~2.5ms with the current stability, or 4ms and much more stable. Which would be perfectly usable.

> RT GI is currently usually around ~4ms, which is at the upper edge of usable. However the temporal stability is usually the bigger issue - at current ray counts, with current algorithms, either noise or slow response times is an inevitable tradeoff. Hence, 70% usable. But with another few years of improvements, we'll probably get to the point where we can get it down to ~2.5ms with the current stability, or 4ms and much more stable. Which would be perfectly usable.

Maybe you should be saying 70% feasible rather than 70% usable. And you seem to be very optimistic about what kind of improvements we can expect for affordable, low-power GPU hardware over a mere 3-5 years. I don't think algorithmic improvements to denoisers and upscalers can get us much further unless we're using very wrong image quality metrics to give their blurriness a passing grade. Two rays per pixel is simply never going to suffice.

Right now, an RTX 4090 ($1700+) runs at less than 50 fps at 2560x1440, unless you lie to yourself about resolution using an upscaler. So the best consumer GPU at the moment is about 70-80% of what's necessary to use path tracing and hit resolution and refresh rate targets typical of high-end gaming in 2012.

Having better-than-4090 performance trickle down to a more mainstream price point of $300-400 is going to take at least two more generations of GPU hardware improvements even with the most optimistic expectations for Moore's Law, and that's the minimum necessary to do path tracing well at a modest resolution on a game that will be approaching a decade old by then. It'll take another hardware generation for that level of performance to fit in the price and power budgets of consoles and laptops.

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