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Faking RTX Global Illumination vs. RTX | 100% Ray-Traced Game, Pt 1

8 videos recommended on HN
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1 HN user recommended this demo1 month2019 score 1
Years with an HN recommendation, 2007–2026

HN uses it as a reference for how noisy raw real-time ray tracing is and how it compares with traditional faked lighting.

Gamers Nexus builds a fully ray-traced demo in Unreal Engine to compare faked global illumination with RTX ray-traced GI. It covers the gains in dynamic scenes and accuracy against the performance cost and noise.

“this extremely interesting video show state of the art techniques used to fake global illumination” (HN, 2019)

1 recommendations · 3 citations · Demos · intermediate · partly dated

4 Hacker News comments

From the HN archive; up to 20 kept per video, favoring different commenters. Recommendations first.

@LoSboccacc Oct 2019 Recommends
on HN thread An Inside Look at Microsoft’s Newest Flight Simulator
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this extremely interesting video show state of the art techniques used to fake global illumination without using ray-tracing and compares the result with the ray-traced variant [this video] long story short moving object color casting light is the main visible difference that cannot be replicated with traditional techniques (like baking the light reflection in the scene at built time, but can be faked convincingly); ray-tracing is also not limited at reflecting elements that are on the scene like what you'd get from screen space reflection, which is less noticeable of an effect but is there if you pay attention and know what to look for.
Techniques faking global illumination compared to ray tracing.

Citations, criticism and jokes

@rolleiflex Mar 2019 Cites it
on HN thread Tensorflow 2.0.0-Alpha0
My impression from the analyses I've seen so far is that it barely improves the visual quality, since the game designers learned to fake it so well over the last two decades, and it comes at a significant cost to frame rate. In particular, good ray-tracing with acceptable noise levels comes at around 500 rays a point. RTX cards are capable of 2 rays a point. Here is a comparison of the regular global illumination vs RTX real-time raytracing, particularly take look at noise levels generated by RTX in the background. [this video]
Compares standard global illumination with RTX noise levels.
@kuzehanka Mar 2019 Cites it
on HN thread Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan
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Path tracing has huge wow factor. The problem with RTX is that on current gen hardware it runs at laughably low sample rates and the result is very noisy even after DLDN. Games are handling this by dialling the amplitude of RTX effects way down and having a smoothing pass. After all that is done, the wow effect is gone and you're just left with a more dynamic version of the same or worse aesthetics that we're already used to. I expect it'll truly take off on next gen hardware, whenever that rolls out. Here's what RTX+DLDN actually looks like if not dialled down and smoothed: [this video] My takeaway is yes that quake 2 demo looks really cool, but you just know that they used every black magic hack in the book to get there, and most of it can't be replicated in a modern high fidelity game. It's definitely not a case of flicking an 'RTX on' switch.
Shows raw noisy RTX output without smoothing.
@missosoup Sep 2019 Cites it
on HN thread Ray Tracing Denoising
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And yet I cite 3 unrelated sources that all corroborate what I said with detailed analysis and you cite.. Opinion? > assuming that's what you mean, since you keep using the term "RTX" and it's unclear what you talk about, whether it's ray tracing or DLSS etc. I use the term the same way NVIDIA uses it. RTX is anything an RTX core accelerates. Still confused? I think that might have been the intention of their marketing team. > very few people seem to contest that scenes where ray tracing is properly artistically used, have superior aesthetic quality This is quantifiable bs. Ray tracing as a technique is superior to rasterisation, but only with sufficient flops. And the current generation of hardware does not yield that critical number. So we get 'ray tracing', but so subdued and limited that existing approaches just flat out look better and also perform better. [this video] Or if you want a more approachable comparison of RTX vs. not-RTX. consider Minecraft+RTX[1] vs. Minecraft+PTGI[2] [1] [link] [2] [link]
Evidence that current RTX looks worse than existing techniques.

Video list and Hacker News comment labels from HackerTube (prompted by @karpathy), released under ODC-By 1.0, built on the open-index/hacker-news archive. Hacker News data is provided by Y Combinator; comments remain the work of their authors. Video titles, channel names and thumbnails belong to their creators and are shown via YouTube. HackerTube Watch is an unofficial edition. Data export of 2026-10-31.

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