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Comment by berkut | Hacker News Reader

Should be "Next-Gen Game Lighting".

This is just Physically-based shading basically, which has been done for the past 4/5 years in VFX. Essentially it's energy-conserving materials with the correct fresnel effect based on the surface's IOR which takes things to the next level (for games at least). Doing this properly for layered surfaces (e.g. diffuse wood layer with a clearcoat varnish layer) gives very nice looking results.

Some complex materials can have up to 3 spectral BSDF lobes for reflection, which can only really be done with pathtracing.

For VFX, people are starting to push into spectral rendering now, and trying to optimise things like volumetric rendering for things like SSS which are needed for ultimate realism.

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OK, I'll don the Captain Jargon outfit and give that a go:

- VFX is just "visual effects", http://en.wikipedia.org/wiki/Visual_effects.

- Fresnel might be a reference to "Fresnel refraction", http://en.wikipedia.org/wiki/Fresnel_diffraction.

- IOR is of course "index of refraction", http://en.wikipedia.org/wiki/Refractive_index.

- BSDF references "bi-directional scattering distribution functions", http://en.wikipedia.org/wiki/Bidirectional_scattering_distri....

- Path tracing is a Monte Carlo method of rendering images with global illumination, http://en.wikipedia.org/wiki/Path_tracing.

- SSS means "sub-surface scattering", http://en.wikipedia.org/wiki/Subsurface_scattering.

+1 - sorry, I do this stuff all day, so am used to the slang :)

Fresnel also effects just reflection as well - it's the reason you don't often (depending on the material) see much of a reflection head-on on a shiny surface, but do at a glancing angle (glass or car paint for example).

What do you work with?

Renderers and shaders for one of the biggest VFX companies in the world :)

I recently implemented Fresnel reflection in my mobile game engine; it's one of those things which makes an objectively small difference but a subjectively large one.

> the reason you don't often see much of a reflection head-on on a shiny surface, but do at a glancing angle

Ah! I've noticed shiny things in real life that made me think "if I saw this in a game, I would think the reflection was overdone." I think what you've mentioned there is the key. The reflections I remember from early 2000s video games seem overdone because they're reflective at all angles. In real life, the shiny marble floor is only really mirror-like at shallow angles, when looking head-on it only appears glossy.

Physically-based shading in games is done very differently from VFX. We're still mostly approximating instead of trying to simulate. We don't event call it "physically-based shading" as that would be lying, our version of it is "physically-based rendering."

Your graphics package physically simulates the light, gamedevs simply try to emulate what would happen were it physically simulated.

PBR has been done before UE4 (The latest CoD has it and I think Frostbite 3). I don't think PBR is directly responsible for what you are seeing in UE4 (it certainly adds to it), it's likely using more recent developments such as deep GBuffers (http://graphics.cs.williams.edu/papers/DeepGBuffer13/).

Gamedevs want to be able to do what you guys do in VFX, but we can't because we have the realtime restriction. We takes leaps like this when we figure out how to do fast approximations of what you guys are doing (and deep GBuffers are such a leap).

Yeah, I think the difference is "Physically-based" and "Physically-plausible" :)

Although strictly speaking a lot of VFX rendering is still about how much you can fake stuff, although it is a lot more real (as in done in the renderer instead of at comp stage) than it was 5/6 years ago.

Kotaku is a video game blog, so "Next-Gen" specifically refers to games running on Playstation 4, Xbox One and sometimes high-end PCs. Specifying "Game" on Kotaku is kind of redundant as almost all technology related posts are referring to games in some way. I could see it on a general technology, art or VFX site though.

The siggraph physically based shading course is a great resource if you're interested in the techniques people are using in production.

2012 - http://blog.selfshadow.com/publications/s2012-shading-course...

2013 - http://blog.selfshadow.com/publications/s2013-shading-course...

2014 (not yet available) - http://blog.selfshadow.com/publications/s2014-shading-course...

The irony being that the point of the article is that if you didn't code for "Next Gen" consoles you'd get all this lovely rendering. The article title is the opposite of what the story is about!

It's been around a lot longer than that (15-20 years?) but only been practical for video and VFX more recently. People have been doing architectural images etc. with pretty complex BSDF for ages.

For those who are interested but new to this, some of the earlier global illumination stuff is a good place to start for the fundamental ideas, because they aren't concerned so much with fast paths in the rendering architectures.

What?

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