Let's Get Physical

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Reedbeta 167 Sep 09, 2013 at 17:33 graphics

Discuss link: Let's Get Physical (rgba32.blogspot.com)

This is an older article about physically-based rendering, but it’s a good one and has been making the rounds on Twitter lately. It also talks about the artistic reasons for doing PBR, not just the technological/scientific ones.

Also, this is a test of what happens when external links are posted.

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rouncer 103 Sep 10, 2013 at 05:37

Physically based… that means path tracing doesnt it?

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TheNut 179 Sep 10, 2013 at 05:51

I’m sort of on the fence as to whether or not PBR will take off in games as much as it benefits 3d modellers. In the real world, movie production requires a tremendous amount of artificial lighting to get the desired footage. Partially this is to make up for the physical limitations of a camera lens (which technically is the same goal we try to simulate with games), but the other part of it is to make the image more artistic and presentable. To achieve the same effects you would have to add the same artificial lighting in the game world. Given that PBR is already computationally expensive (even with a bias renderer), to add artificial lighting on top of that would require even more processing power. So the choice becomes messing with artificial lighting or messing with the equations, thus skewing the definition of PBR.

I think when hardware reaches a point where we can achieve 60 fps with an unbias renderer on any given scene, then perhaps it might have use. I say perhaps because there’s likely to be a legal cloud surrounding its use in interactive media. I can’t imagine for instance a violent game using such quality. It will create moral boundaries that games with today’s technology can at least wiggle with. For other games, I don’t know. Do I want to see a real sunset or do I want to see a fake, imaginary, cartoony CGI generated sunset? Perhaps it’s just me, but I fancy the fake and unreal.

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rouncer 103 Sep 10, 2013 at 05:57

That little big world game looks amazing tho, I wonder if it was just clever use of textures tho? and it looks physically based anyway?

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Reedbeta 167 Sep 10, 2013 at 16:55

PBR doesn’t necessarily mean path tracing. It basically means leaving behind ad-hoc, phenomenological models like Phong shading, and using models and algorithms with a physical basis behind them, e.g. realistic energy-conserving BRDFs, making sure different components of the lighting equation match (e.g. specular highlights and environment reflections should have the same reflection coefficient), physically correct light attenuation curves, and stuff like that. I wrote a longer post on Gamedev StackExchange about it. This stuff has already taken off in games, as numerous AAA games of the last few years, as well as all the major engines, are doing it.

Path tracing, photon mapping, etc. are eventual goals; sure, it would be great to do that stuff in real time, and people are working toward it but we’re not there yet. That doesn’t mean you can’t still use PBR to good effect in games.

Also, just because the rendering is physically-based doesn’t mean the art has to be in a realistic style. People have done and will continue to do stylized or cartoony CGI using physically-based lighting and shading. Look at Monsters University for example. And as the rgba32 blog post pointed out, there’s still a lot of room for different styles, moods, etc. based on what you do with the art.

As for hyper-realistic rendered violence (or porn for that matter), that’s certainly a debate worth having, but there’s no way that it’s going to throw up a “legal cloud” around real-time PBR techniques. That makes no sense.

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TheNut 179 Sep 11, 2013 at 06:21

I don’t disagree with you, I just want to draw the line between a bias vs unbias renderer. Improvements in hardware have enabled us to take advantage of better lighting models; however they are still approximations and a far cry from a true, unbias renderer. And yes, I’m very picky about quality :)

As for artistic style and lighting, they do fall under the same branch. Take Team Fortress 2. This is why I said I’m not sure how I would feel. If that game had PBR equivalent to a Pixar movie, it would totally change the mood. I’m not sure for better or worse, but my opinion now would be to favour the fake approach they have today. So the line between real and unreal needs to be drawn carefully. It’s like not one solution fits all.

As for the legal matter, I speak on behalf of products, not the engineering. GTA was heavily criticized despite being easily recognizable as fake. Or even that manslaughter game that was banned (I think it’s now globally banned?). Imagine you anti up to photorealistic humans that you slit their throat or put a plastic bag over their head and watch them suffocate. Or the next CoD where you put a bullet into an unmistakably realistic human. Well, that’s a completely different ball game. I don’t think society is going to sit back and laugh as they blow holes into real looking people. It just won’t fly.

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tyree 102 Sep 10, 2013 at 17:04

physical based shaders have been in 3d programs for some time. trying to do a physical based render was the next step

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fireside 141 Sep 10, 2013 at 18:32

I’m kind of with the side that thinks it will make games look even more alike. I thought the whole purpose of shaders was to give games a different look from one another.

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tyree 102 Sep 11, 2013 at 04:28

to fireside 3d as a whole has been dealing with everything appearing the same. since its inception. not just the way it is rendered but motion also. this is largely due to the pursuit of realism. the game ico which went in the opposite direction of realism caused bloom lighting to be included in engines.

the person that made ico took a look thats common in anime, used to signify an emotion and carried it thru the whole game. with perfection. but again not pursuing realism. but an artistic way to reach an emotion. now when I see it used as a generic effect. yes it can make a scene look better. but its empty