4.0A producing specular reflections of area lights on diffuse surfaces, 3.6.1 doesn't behave this way. #111125

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opened 2023-08-14 23:54:48 +02:00 by Christopher Tyler · 3 comments

Christopher Tyler commented

2023-08-14 23:54:48 +02:00

System Information
Operating system: macOS-13.4.1-arm64-arm-64bit 64 Bits
Graphics card: Metal API Apple M1 Pro 1.2

Blender Version
Broken: version: 3.6.1 & 4.0 Alpha, branch: blender-v3.6-release, commit date: 2023-07-17 12:50, hash: 8bda729ef4dc
Worked: (newest version of Blender that worked as expected)

Short description of error
Area lights in 4.0 Alpha producing specular reflections on diffuse only (specular = 0) surfaces in 4.0.

Exact steps for others to reproduce the error
I tried to report this discrepancy to the developer forum but can't seem to post it there, so I figured maybe whoever monitors this could help.

In 3.6.1, if a material has no specular component, area lights only produce diffuse illumination. But in the 4.0 alpha (build downloaded 8/14), the area light produces a specular reflection. I don't know if this is a new intentional development thing, or if it's somehow related to the light linking feature.

**System Information** Operating system: macOS-13.4.1-arm64-arm-64bit 64 Bits Graphics card: Metal API Apple M1 Pro 1.2 **Blender Version** Broken: version: 3.6.1 & 4.0 Alpha, branch: blender-v3.6-release, commit date: 2023-07-17 12:50, hash: `8bda729ef4dc` Worked: (newest version of Blender that worked as expected) **Short description of error** Area lights in 4.0 Alpha producing specular reflections on diffuse only (specular = 0) surfaces in 4.0. **Exact steps for others to reproduce the error** I tried to report this discrepancy to the developer forum but can't seem to post it there, so I figured maybe whoever monitors this could help. In 3.6.1, if a material has no specular component, area lights only produce diffuse illumination. But in the 4.0 alpha (build downloaded 8/14), the area light produces a specular reflection. I don't know if this is a new intentional development thing, or if it's somehow related to the light linking feature.

Area Specular 3,6.jpg

503 KiB

Area Specular 4,0A.jpg

534 KiB

Area Specular 3,6.jpg

Area Specular 4,0A.jpg

Christopher Tyler added the

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Iliya Katushenock added the

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label 2023-08-14 23:58:37 +02:00

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Alaska commented

2023-08-16 01:47:23 +02:00

Member

What is your IOR? If it isn't 1.0, then reflections will appear. This is caused by a recent change to the Principled BSDF made by @LukasStockner .

This may seem like a weird change, but from my understand it's supposed to better match the way lights and materials work in real life.

What is your IOR? If it isn't 1.0, then reflections will appear. This is caused by a recent change to the Principled BSDF made by @LukasStockner . This may seem like a weird change, but from my understand it's supposed to better match the way lights and materials work in real life.

Christopher Tyler commented

2023-08-16 01:49:58 +02:00

Author

What is your IOR? If it isn't 1.0, then reflections will appear. This is caused by a recent change to the Principled BSDF made by @LukasStockner .

This may seem like a weird change, but from my understand it's supposed to better match the way lights and materials work in real life.

Yes, thank you. As I dug into the the latest 4.0 alpha, I realized that's probably what it was, now that they have IOR controlling reflectivity, specular can still independently allow the specular highlight of direct light sources. So, doesn't look like a bug, just that I didn't realize what was happening. Thanks for getting back to me.

> What is your IOR? If it isn't 1.0, then reflections will appear. This is caused by a recent change to the Principled BSDF made by @LukasStockner . > > This may seem like a weird change, but from my understand it's supposed to better match the way lights and materials work in real life. Yes, thank you. As I dug into the the latest 4.0 alpha, I realized that's probably what it was, now that they have IOR controlling reflectivity, specular can still independently allow the specular highlight of direct light sources. So, doesn't look like a bug, just that I didn't realize what was happening. Thanks for getting back to me.

Lukas Stockner commented

2023-10-04 14:23:39 +02:00

Member

Should be fixed by #112552, setting Specular=0 now again gives the same render as if IOR was set to 1.0.

Should be fixed by #112552, setting Specular=0 now again gives the same render as if IOR was set to 1.0.

Lukas Stockner closed this issue

2023-10-04 14:23:43 +02:00

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labels 2023-10-04 14:23:45 +02:00

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