How Ray Tracing works and how to do it faster [video] | Hacker News Reader

How Ray Tracing works and how to do it faster [video]

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168 pointsnikolay16 comments

We know about this video and lots of indie math explainer videos like it thanks to 3Blue1Brown's "summer of math exposition". if you haven't heard about it, think of it as the best binge watch drop ever

https://youtu.be/cDofhN-RJqg

Another video in #SoME2 about ray tracing: https://www.youtube.com/watch?v=hCdqapTI63k

This is an amazingly well presented video.

That was a well explained video. Thanks for the share.

really good video that updated my knowledge from thirty years old to 15 years old. All the probabilistic modelling is really cool!

Faster as in having something newer than Quake 2 run with 120 on modern hardware?

By the time we have ray/path traced global illumination in a $current_year game, all of my hair would be white

A lot of current games use ray tracing as an addition to classical rasterization but NVIDIA Racer X[1] is a new tech demo/game that doesn't use any pre-baking. It's not a "real game" released by a game studio but it proves hardware is strong enough for completely simulated lighting if utilized correctly.

[1] https://www.youtube.com/watch?v=GBYs4y1BtGg

Really? That is a carefully directed video with a cool audio track. Have you tried running the actual tech demo?

I would not be that sure about that (although, admittedly I don't know the state of your hair, so maybe the timespan till all your hair is white is shorter than one might guess?)

Very basic geometry renders with all bells and whistles (refraction, reflection, complex normals, sheen effect, global illumination with both refractive and reflective caustics) in sub 2 seconds in the latest blender builds on a somewhat decent laptop with a RTX2080. The same thing would have rendered for a good minute on a decent machine a few years back.

And Blender is not even meant to do that realtime as it is not a game engine (anymore). So sure, going from 1.5 seconds to 1/60 seconds is a huge step, but similar steps have been made in a decade.

I am just that annoying guy trying to remind everyone Q2 RTX is still the best we've got in terms of actual games. Take that at face value. It barely runs on ~6 year old gpu.

I was about to pull a few numbers out of my ass as to how it must on a 3090 but then I thought someone on youtube must've done it already. And they have[0]. 52 fps is not great. I am no game maker of any kind but even my non-pro eyes can tell modern titles have way more geometry so the best we've got out of them is shiny surfaces and fake GI like in Metro.

[0] https://www.youtube.com/watch?v=dVS2zwqeUaU

That said, I am eager to get my hands on that mythical ray traced RTCW someone at AMD has been working on.

Honest to goodness the results don't seem worth it for the power usage. Pre-baked lighting, environment maps, material shaders look _really good_ and are easy to get decent frame rates out of without sacrificing artistic freedom. Why are we making it more difficult for ourselves with global illumination which just introduces more problems. It's just very difficult to realistically light things while still maintaining high-visibilty of game assets in dynamic situations.

It sells graphics cards but I just don't think it's very practical.

My condolences for the imminent loss of hair color.

I am just morphing into my Targaryen form, only without the dragons and everything else that makes them special.

I thought raytraced GI was pretty unexceptional these days, Metro Exodus did that already back in 2018: https://www.youtube.com/watch?v=Ms7d-3Dprio

Yes, ray traced GI in Metro was pretty unimpressive.

Global illumination is a very broad topic, and there are many different implementations at different levels of approximation.

Metro Exodus used one version that I think was one bounce only, and heavily denoised. The Enhanced Edition added probe based GI, which is infinite bounce but only captures low frequency lighting. Lumen uses surface caching, which is expensive and has low frequency temporal noise, but is higher quality yet. This video was probably covering ReSTIR GI, which is a much more advanced newer technique that has a diffuse surface approximation for multi-bounce but is otherwise almost unbiased, but might have been referring to the even newer GRIS, which can be actually fully unbiased.

So... yes and no? Some GI is unimpressive, though IMO Metro Exodus' still holds up, but the cutting-edge stuff you can only see in tech demos right now.

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