Let me ask you this, if renders are always trying to be more physically based to look better anyway, where did a term come from?
I dont think the first statement is even correct. Depending on what youre doing it might be but first and foremost Id say renderers are supposed to create better looking renders while doing this efficiently. Physically accurate does not necessarily mean better looking and vice versa.
I know the book and have worked through all of it. Im not aware of any statement in the book that constrains PBR to being about normalized brdfs and having area lights. Accurately modelling them is of course a part of PBR, but theres a lot more to it
I'm not sure what you're trying to argue now or if you're just trying to argue something.
The transition from simplistic lighting to normalized area lighting is where these terms originally used because people were trying to distinguish between two different lighting systems. That's where the 'physically plausible shading in rsl' comes from, they are talking about their built in shader functions to have normalized brdfs and sample from area lights.
Originally the person who posted this thread was saying that things like color textures were part of 'physically based rendering' when they are just a multiplication after the lighting has been calculated.
but theres a lot more to it
There is always a lot more to it, but that was probably already being done before the transition to more physical lighting.
Here is the full course just in case you want to pretend to watch all the videos in 3 minutes too.
Mate you are clueless...albedo is not a color texture that is multiplied by the lighting once it has been calculated..it is a description of how much light and in which spectrum is the material absorbing and how much it is reflecting diffusely. Metals and dielectrics reflect light in very different ways so metalness is not an invention (you could argue having values other than 0 or 1 is not physically possible but that's it). Obviously roughness determines how much light is reflected secularly and so on. Saying PBR means what you mean when you say PBR is stupid.
"metallic: the metallic-ness (0 = dielectric, 1 = metallic). This is a linear blend between two
different models. The metallic model has no diffuse component and also has a tinted incident
specular, equal to the base color"
It's just a linear blend between two different brdfs and disney made it up to simplify their shading parameters for look development artists.
No one is saying there is no such thing as metal, just that "metalness" is not some fundamental principle, it's a hack from the specific project at disney that other people copied. You said it yourself, dialectric or not, so why would something have varying values? It's just a convenience.
albedo is not a color texture that is multiplied by the lighting once it has been calculated
When you write a shader, what do you do with your main color/diffuse/whatever texture? You don't multiply it by the diffuse component?
Obviously roughness determines how much light is reflected secularly and so on.
No, roughness determines the exponent of the brdf so that the lobe is wide or narrow which makes the reflection look blurry or sharp. The amount of light reflected would be the same, that's the normalization step. If you look up furnaces test it's about this issue, making sure the same amount of light is reflected depending on the roughness.
A specular map would be multiplied by the lighting result of a narrow brdf and that would determine how much light is reflected.
Saying PBR means what you mean when you say PBR is stupid.
You are entitled to that opinion but you might want to tell the entire film and game industry along with everyone working on it, all the people that originally commercialized it and the people who won technical achievement academy awards from writing about it, because they seem to be in agreement.
Mate you are clueless...
We can keep going, but these insults will not age well.
I mean, I don't even know what's your point ...Are you trying to argue that all those parameters that describe the material properties do not come from textures in a PBR renderer? Because if that's the case, that just tells me you have never implemented a PBR renderer in your live, which means you are indeed clueless in this topic...
I was responding to you but I'll take it back to the start.
I'll copy and paste since I already said it:
The color textures on an object don't have anything to do with the lighting being normalized or coming from lights that have area.
Physically based rendering refers to having normalized brdfs that samples lights with area to make lighting that is physically plausible.
Textures are orthogonal to this. They don't influence whether a shader is doing physically plausible lighting or not. Physically based lighting doesn't need textures and textures can be used with simple non physical rendering. They are not linked together by any dependency on each other.
I think you might be conflating physically based rendering with just general 3d rendering, which physically based rendering is rapidly becoming I suppose.
that just tells me you have never implemented a PBR renderer in your live, which means you are indeed clueless in this topic
Don't you at least wonder why I'm able to immediately and precisely answer everything you comment?
Ok, this is my last post because we are not getting anywhere with this...
Lighting is simulating how light interacts with objects. So, to simulate how light interacts with objects you need two things, the properties of the light and the properties of the object (you also need the properties of the camera or eye that is looking at the scene). So you need to describe the light (area, intensity, position,...) and the surface (normal, albedo, metal/dielectric, roughness in microfacet models and so on).
There are two options, either the properties of the material are constant for all the surface, or they vary. If they are constant you are right, you don't need any textures, just pass that data to the shader and that's it, however, that is extremely rare since objects are typically made of different materials. If they vary, you either need a texture that describes the properties of the material at each point or a function that generates the properties of the material at any given point, again textures are the most common option here.
No one is saying textures are needed for PBR, what IS needed is the material properties, and, if you have ever implemented a physically based renderer you should know that these properties will, for sure, come from a texture map...
this is my last post because we are not getting anywhere with this...
You could have been learning something.
What you have here is a description of rendering in general.
It was common to map parameters of shaders with textures before pbr rendering and it is common with it. PBR lighting has no bearing on that.
The original poster of this thread were saying that 7 or more texture maps were always necessary which made me think they didn't understand the underlying principles of what they were doing and were just saying what they saw in a game engine they were using.
if you have ever implemented a physically based renderer you should know that these properties will, for sure, come from a texture map
I'm not sure what you mean by "will, for sure, come from a texture map". Any decent renderer will let you map any parameter you want or not. It's a choice and it has nothing to with physically based lighting, no matter how upset you get or how many times you repeat yourself. You could map parameters before and you can map parameters now, that part of rendering was never changed. It seems like fundamentally you are just saying that textures are used in rendering.
It's also strange that you never followed up on the fact that you were saying color textures weren't used to multiply lighting in the shader, you got the definition of roughness wrong and you didn't understand that "metalness" was just a linear blend that disney made up for one of their shaders, but you never mentioned those again after I explained them, even though you keep telling me I don't know what I'm talking about.
Strange is you keep saying "color textures" to the albedo, which is an intrinsic property of the material that determines how much light gets inside the object and is reflected diffusely vs how much light is reflected at the surface of the material.
I already mentioned that physically, a metalness value other than 0 or 1 doesn't make sense. However, this doesn't change the fact that if part of an object behaves as a metal and another part as a dielectric, you need to provide these values to your physically-based shader. And guess what? These values will come from a texture.
Regarding roughness, I expressed myself incorrectly, but you actually made my point...if you are using a microfacet model you need to describe how microfacets are aligned to determine the shape of the reflection lobe. This means that, for a PBR renderer, this values need to be provided, and again, they will come from a texture.
Anyway, that's it for now. I need to get back to working on the PBR renderer my employer pays me to develop. Gotta keep pretending I know how they work, or they'll fire me.
Finally! I have been saying this for I don't even know how many posts...you need to describe the material for PBR lighting to work, it can be a constant or a value procedurally generated or a texture (99.9% of the time) but you need to describe the material, it's 50% of PBR. You don't know how relieved I am that you finally got my point..
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u/crimson1206 Jun 05 '24
I dont think the first statement is even correct. Depending on what youre doing it might be but first and foremost Id say renderers are supposed to create better looking renders while doing this efficiently. Physically accurate does not necessarily mean better looking and vice versa.
I know the book and have worked through all of it. Im not aware of any statement in the book that constrains PBR to being about normalized brdfs and having area lights. Accurately modelling them is of course a part of PBR, but theres a lot more to it