Glossy direct render pass deliver texture information. #53984

New Issue

Kamil Adamski · 2018-02-02T15:08:18+01:00

Kamil Adamski commented

2018-02-02 15:08:18 +01:00

System Information
Windows 10 Pro, GTX 970

Blender Version
Broken: Official 2.79
Worked: none

Short description of error

When an object is textured, and render passes are used to do final composite from render passes, glossy direct render pass deliver texture information from diffuse.
There are no other textures, only albedo. also environment isn't present. Solid color.

In this case, We are unable to use Blender UV pass, to change texture in compositor (for example product renderings, where We need studio lighting, and the object is floating in space). This is a huge problem.

Exact steps for others to reproduce the error
I'm attaching simple blend file. Just hit render, go to composite nodes and take a look at glossy direct pass, but look closely (if needed brighten this pass to see it better).
GlossyTest.blend

**System Information** Windows 10 Pro, GTX 970 **Blender Version** Broken: Official 2.79 Worked: none **Short description of error** When an object is textured, and render passes are used to do final composite from render passes, glossy direct render pass deliver texture information from diffuse. There are no other textures, only albedo. also environment isn't present. Solid color. In this case, We are unable to use Blender UV pass, to change texture in compositor (for example product renderings, where We need studio lighting, and the object is floating in space). This is a huge problem. **Exact steps for others to reproduce the error** I'm attaching simple blend file. Just hit render, go to composite nodes and take a look at glossy direct pass, but look closely (if needed brighten this pass to see it better). [GlossyTest.blend](https://archive.blender.org/developer/F2092290/GlossyTest.blend)

Kamil Adamski commented

2018-02-02 15:08:18 +01:00

Added subscriber: @adrian2608

Brecht Van Lommel commented

2018-02-03 10:08:36 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2018-02-03 10:08:36 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2018-02-03 10:08:36 +01:00

Brecht Van Lommel self-assigned this 2018-02-03 10:08:36 +01:00

Brecht Van Lommel commented

2018-02-03 10:08:36 +01:00

I'm afraid there's no good way to fix this. In the Principled / Disney shader design, the base color affects Fresnel, which causes this variation in the Glossy Direct pass. If we move the Fresnel influence to the Glossy Color pass, that doesn't help either to replace the texture. If we leave it out, the original render can't be recovered.

In general once you do more advanced shading and global illumination, some of the assumptions you need to make to do texture replacement in compositing break down. I don't think we'd want to change the Principled Shader to be a bit less realistic to try to compensate for this.

Why are you rendering with a base color texture instead of an even color though? Or do you just want to replace the specular texture, and in that case, maybe this Fresnel factor is not actually a bad thing?

I'm afraid there's no good way to fix this. In the Principled / Disney shader design, the base color affects Fresnel, which causes this variation in the Glossy Direct pass. If we move the Fresnel influence to the Glossy Color pass, that doesn't help either to replace the texture. If we leave it out, the original render can't be recovered. In general once you do more advanced shading and global illumination, some of the assumptions you need to make to do texture replacement in compositing break down. I don't think we'd want to change the Principled Shader to be a bit less realistic to try to compensate for this. Why are you rendering with a base color texture instead of an even color though? Or do you just want to replace the specular texture, and in that case, maybe this Fresnel factor is not actually a bad thing?

Kamil Adamski commented

2018-02-05 13:11:49 +01:00

Hi Brecht,

I'm doing product renderings, where sometimes are 10 different textures, but fitting the same model, and the same UV space. So then if I want to save time (and to be honest, this is a lot time saved), I do it in compositor as I describe in the topic. To replace Direct Color pass in compositor with UV pass. Specular texture isn't present here at all. Just a little overall reflection.

Also this isn't "Principled" shader issue, it works like this with any other shader with glossiness (CynicatPro shader, or just glossy diffuse mix).

Another thing is, that on other project, direct pass isn't delivering anything from albedo texture. The same technique, to replace label from a Peanut Butter product.
Attaching renders. Principled shader.

Hi Brecht, I'm doing product renderings, where sometimes are 10 different textures, but fitting the same model, and the same UV space. So then if I want to save time (and to be honest, this is a lot time saved), I do it in compositor as I describe in the topic. To replace Direct Color pass in compositor with UV pass. Specular texture isn't present here at all. Just a little overall reflection. Also this isn't "Principled" shader issue, it works like this with any other shader with glossiness (CynicatPro shader, or just glossy diffuse mix). Another thing is, that on other project, direct pass isn't delivering anything from albedo texture. The same technique, to replace label from a Peanut Butter product. Attaching renders. Principled shader. ![Beauty.jpg](https://archive.blender.org/developer/F2130174/Beauty.jpg) ![Glossy direct.jpg](https://archive.blender.org/developer/F2130178/Glossy_direct.jpg)

Kamil Adamski commented

2018-02-06 16:13:25 +01:00

Hi again,

I see this task is closed, but there is something wrong. Why in one case this is good, and in another not? With the same shader, without any other textures except albedo?
On the jar We can clearly see that everything is good. So maybe this is a bug?

Please explain it better if You can Brecht, because I don't understand.

Regards,
Kamil.

Hi again, I see this task is closed, but there is something wrong. Why in one case this is good, and in another not? With the same shader, without any other textures except albedo? On the jar We can clearly see that everything is good. So maybe this is a bug? Please explain it better if You can Brecht, because I don't understand. Regards, Kamil.

Brecht Van Lommel commented

2018-02-06 16:35:54 +01:00

How much the albedo influence the glossy passes depends on the Principled BSDF settings and light setup. I just verified that in the attached .blend it was due to the way the Principled BSDF handles Fresnel, and that this does not appear to be a bug. Why it does or does not happen in other specific files I can't guess, but in general the fact that it changes by file is not indicative of a bug. This file for example uses specular tint and clearcoat, others might not.

From what I understand though, for your case it should be possible to render with a fixed base color to avoid any variation in the glossy passes?

How much the albedo influence the glossy passes depends on the Principled BSDF settings and light setup. I just verified that in the attached .blend it was due to the way the Principled BSDF handles Fresnel, and that this does not appear to be a bug. Why it does or does not happen in other specific files I can't guess, but in general the fact that it changes by file is not indicative of a bug. This file for example uses specular tint and clearcoat, others might not. From what I understand though, for your case it should be possible to render with a fixed base color to avoid any variation in the glossy passes?

Kamil Adamski commented

2018-02-06 17:07:33 +01:00

Apologize, it occurs also on the jar. Very subtle but it's there.

So basically there is no way to somehow get around it?

Apologize, it occurs also on the jar. Very subtle but it's there. So basically there is no way to somehow get around it?

Brecht Van Lommel commented

2018-02-06 18:28:42 +01:00

I guess the only workaround is to not use the Principled BSDF, or render with a fixed base color as I suggested.

Kamil Adamski commented

2018-02-06 19:03:30 +01:00

This isn't in Principled, this is always when glossy shader is used. I've tested it with only glossy with diffuse, and it's the same.
I also tested it with CynicatPro shaders and the same. Fixed base color should work well in this scenario. Thank You for pointing this out.

Best Regards,
Kamil.

This isn't in Principled, this is always when glossy shader is used. I've tested it with only glossy with diffuse, and it's the same. I also tested it with CynicatPro shaders and the same. Fixed base color should work well in this scenario. Thank You for pointing this out. Best Regards, Kamil.

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Glossy direct render pass deliver texture information. #53984