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Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

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Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#111

Post by dahart »

pornel wrote: post #38

I love RTX, but it's so hard to demonstrate it. It doesn't give presence of any "wow!" effect (apart from demos that overdo reflections), it only gives absence of incorrect shadows, and humans are bad at noticing absence of things. Instead of "wow" you get "well, duh, that's how things should look".

That’s a good way to put it. There’s some kind of uncanny valley of rendering, I think. Not exactly the same idea, but I noticed this starting decades ago while playing on an SGI- the demos with flat shading oddly seem more impressive than the ones that had an environment map and chrome reflections. It felt like the computer was doing more work when the image was less realistic, and the more realistic it got, the less it felt like billions of amazing calculations were happening under the hood. It’s still true, and it’s ironic when I’m seeing these amazing demos today with real time path tracing and astounding amounts of complexity, the visceral feeling is more like looking at photos than amazement for how incredible the rendering is. I have to force myself to think harder about what’s going on in order to appreciate it.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#112

Post by tntn »

woodrowbarlow wrote: post #106

can someone help me understand what "ray tracing" means in this case? i've read a few technical articles about ray-tracing, but they mostly describe it as a rudimentary (largely outdated) way of achieving 3d effects with relatively little code, and with severe limitations (walls must be orthonormal, changes in elevation require extra work, etc.). i understand ray-tracing at this level (break the view into columns, se…

Sounds like the first thing you are describing is closer to ray casting. Ray tracing doesn't have the limitations you mention.

Roughly speaking, ray tra in techniques are variations on the concept of tracing a ray from the camera back into the screen and seeing where is ends up. The different variations distinguish themselves by what happens at a ray intersection. Classical ray tracing will spawn a shadow ray towards light source. Path tracing will stochastically sample some distribution of ray directions (usually based on a combination of light locations and material properties) in order to do Monte Carlo integration of the rendering equation. There are other variations.

Ray tracing (w/ only shadow rays) doesn't give you global illumination. Path tracing (this work) does.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#113

Post by hellofunk »

dahart wrote: post #98
seanalltogether wrote: post #68

Earlier quoted context omitted.

I thought path tracing was just ray tracing with additional random scatters traced, is it not?

Depends on who you ask, the term is overloaded now. These days, it does tend to mean doing global illumination using ray tracing. Originally, the term “path tracing” was used to refer to taking a single random scatter at every step along a path of connected segments, as opposed to the idea of taking multiple random scatters at a point and averaging them, recursively. It’s a way of thinking of Monte Carlo rendering as…

If I’m not mistaken, for your last paragraph, general visibility tests for lines that does not otherwise involve actual rendering is typically just called ray casting.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#114

Post by xsmasher »

woodrowbarlow wrote: post #106

can someone help me understand what "ray tracing" means in this case? i've read a few technical articles about ray-tracing, but they mostly describe it as a rudimentary (largely outdated) way of achieving 3d effects with relatively little code, and with severe limitations (walls must be orthonormal, changes in elevation require extra work, etc.). i understand ray-tracing at this level (break the view into columns, se…

The technique you are talking about, used for Wolfenstein 3D in the '92, is more commonly called "ray-casting." You cast one ray per screen X (or fewer) and see what object it hits, and then draw a slice of that object. https://en.wikipedia.org/wiki/Ray_casting

Ray tracing as used here means simulating light rays bouncing off of objects - it's a high fidelity technique generally not used in games in the past, because it is so slow. https://en.wikipedia.org/wiki/Ray_tracing_(graphics)

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#115

Post by dahart »

hellofunk wrote: post #113
dahart wrote: post #98

Earlier quoted context omitted.

Depends on who you ask, the term is overloaded now. These days, it does tend to mean doing global illumination using ray tracing. Originally, the term “path tracing” was used to refer to taking a single random scatter at every step along a path of connected segments, as opposed to the idea of taking multiple random scatters at a point and averaging them, recursively. It’s a way of thinking of Monte Carlo rendering as…

If I’m not mistaken, for your last paragraph, general visibility tests for lines that does not otherwise involve actual rendering is typically just called ray casting.

You’re not mistaken, ray casting would be more common, but ray tracing is also used. This is especially true among people that design path tracing renderers where we consider “ray tracing” to be a visibility primitive. “Trace a ray” and “cast a ray” are synonymous. I also think using “ray tracing” for visibility might start become more popular now with RTX hardware since the “ray tracing” hardware only provides the visibility test, not a renderer.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#116

Post by echeese »

kuzehanka wrote: post #41
pornel wrote: post #38

I love RTX, but it's so hard to demonstrate it. It doesn't give presence of any "wow!" effect (apart from demos that overdo reflections), it only gives absence of incorrect shadows, and humans are bad at noticing absence of things. Instead of "wow" you get "well, duh, that's how things should look".

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…

What's DLDN? I tried Googling it with some relevant keywords but it just brings me back to this comment.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#117

Post by zamalek »

pornel wrote: post #38

I love RTX, but it's so hard to demonstrate it. It doesn't give presence of any "wow!" effect (apart from demos that overdo reflections), it only gives absence of incorrect shadows, and humans are bad at noticing absence of things. Instead of "wow" you get "well, duh, that's how things should look".

> humans are bad at noticing absence of things.

Until you ask them whether a scene is a photo or a render. They won't know to look for shadow acne, but they will still make a judgement that includes it. RTX has a few things that we've had for years, but it seems to do a way better job at energy preservation.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#118

Post by tntn »

kllrnohj wrote: post #108
woodrowbarlow wrote: post #106

can someone help me understand what "ray tracing" means in this case? i've read a few technical articles about ray-tracing, but they mostly describe it as a rudimentary (largely outdated) way of achieving 3d effects with relatively little code, and with severe limitations (walls must be orthonormal, changes in elevation require extra work, etc.). i understand ray-tracing at this level (break the view into columns, se…

What you are describing sounds more like ray casting than ray tracing. Ray casting is the old Wolfenstein 3D look: https://en.wikipedia.org/wiki/Ray_casting Ray tracing is what Pixar uses for Toy Story, Monsters Inc, etc... https://en.wikipedia.org/wiki/Ray_tracing_(graphics) And then the new hotness for offline rendering is Path Tracing, which is a form really good but really hard to accelerate form of ray tracing:…

I'm pretty sure toy story 1 didn't use ray tracing. Iirc cars was the first that did.

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#119

Post by [deleted] »

woodrowbarlow wrote: post #106

can someone help me understand what "ray tracing" means in this case? i've read a few technical articles about ray-tracing, but they mostly describe it as a rudimentary (largely outdated) way of achieving 3d effects with relatively little code, and with severe limitations (walls must be orthonormal, changes in elevation require extra work, etc.). i understand ray-tracing at this level (break the view into columns, se…

[deleted]

Re: Quake II RTX: Re-Engineering a Classic with Ray Tracing Effects on Vulkan

#120

Post by tntn »

leowoo91 wrote: post #55
lanevorockz wrote: post #37

Earlier quoted context omitted.

RTX is based on the Turing architecture that is a pretty amazing beast. The technology of raytracing has been around or a long time through iray what nvidia did is to bake in the necessary formats, neat interface and slight hardware adjustments.

I only worry about the number of cores being used in these demos. Tech might be same but it's quite possible Nvidia could use their high-energy prototypes to enhance the results. There is no restrictions on that. Clear statements like, "we are using the exact same RTX card we are shipping to consumer in September" would really be a selling point for me.

I think Titan RTX is a "perfect die," so to speak, so even if they used the maximum number of cores they possibly could for this demo, that same silicon is for sale.
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