Blurry reflections from mirror surface when using Principled BSDF in Blender 2.79 test build #52152

Closed
opened 2017-07-22 18:11:59 +02:00 by Ake Johansson · 8 comments

System Information
Windows 7 64 bit with NVIDIA Quadro K2100M
Windows 10 64 bit with NVIDIA GTX 1080

Blender Version
Broken: 2.78.5 a27b6ae

Short description of error
When using the Principled BSDF shader with "Metallic = 1" and "Roughness = 0" (all other values default) reflections are blurry. Comparing with Glossy BSDF with "Roughness = 0" which gives perfectly sharp reflections.

Exact steps for others to reproduce the error
Use the attached blend file to setup the following simple scenario:

  • Create a horizontal and a vertical plane
  • Give the vertical plane a checker texture (or use a bitmap with details like a tree with branches)
  • Define a Glossy BSDF shader for the horizontal plane with "Roughness = 0" (i.e. a mirror surface)
  • The reflection in the horisontal plane is sharp
  • Change the shader for the horizontal plane to a Principled BSDF with "Metallic = 1" and "Roughness = 0", all other values default.
  • The reflections are now significantly blurred

I have tested this with a bitmap on a plane as well as a 16k HDRI with same result. I understand that the Principled BSDF shader is used for real life materials, and there is not a 100% reflecting material, but in my humble opinion, the refelection is way more blurry that what you would see in a real mirror.

Please see screenshots in this question on Blender Stack Exchange. The problem has been reproduced by another user besides me.

Note! Changing the Glossy BSDF to "Roughness = 0.001" gives similar results as the Principled BSDF with "Roughness = 0".

blurred_reflection.blend

**System Information** Windows 7 64 bit with NVIDIA Quadro K2100M Windows 10 64 bit with NVIDIA GTX 1080 **Blender Version** Broken: 2.78.5 a27b6ae **Short description of error** When using the Principled BSDF shader with "Metallic = 1" and "Roughness = 0" (all other values default) reflections are blurry. Comparing with Glossy BSDF with "Roughness = 0" which gives perfectly sharp reflections. **Exact steps for others to reproduce the error** Use the attached blend file to setup the following simple scenario: - Create a horizontal and a vertical plane - Give the vertical plane a checker texture (or use a bitmap with details like a tree with branches) - Define a Glossy BSDF shader for the horizontal plane with "Roughness = 0" (i.e. a mirror surface) - **The reflection in the horisontal plane is sharp** - Change the shader for the horizontal plane to a Principled BSDF with "Metallic = 1" and "Roughness = 0", all other values default. - **The reflections are now significantly blurred** I have tested this with a bitmap on a plane as well as a 16k HDRI with same result. I understand that the Principled BSDF shader is used for real life materials, and there is not a 100% reflecting material, but in my humble opinion, the refelection is way more blurry that what you would see in a real mirror. Please see screenshots in [this question](https://blender.stackexchange.com/questions/85140/blurry-reflections-using-principled-bsdf-in-blender-2-79-test-build) on Blender Stack Exchange. The problem has been reproduced by another user besides me. **Note!** Changing the Glossy BSDF to "Roughness = 0.001" gives similar results as the Principled BSDF with "Roughness = 0". [blurred_reflection.blend](https://archive.blender.org/developer/F675434/blurred_reflection.blend)
Author

Changed status to: 'Open'

Changed status to: 'Open'
Author

Added subscriber: @akej74

Added subscriber: @akej74
Member

Added subscribers: @Sergey, @Blendify

Added subscribers: @Sergey, @Blendify
Member
Glossy Principled
glossy.jpg principled.jpg
|Glossy|Principled| | -- | -- | |![glossy.jpg](https://archive.blender.org/developer/F675597/glossy.jpg)|![principled.jpg](https://archive.blender.org/developer/F675599/principled.jpg)|

Added subscriber: @JasonClarke

Added subscriber: @JasonClarke

This issue was referenced by blender/cycles@ad1267ee9e

This issue was referenced by blender/cycles@ad1267ee9eba564764aead25420b11af1b4da822

This issue was referenced by e982ebd6d4

This issue was referenced by e982ebd6d4f121f7429831bf207fcdca0256ca6f

Changed status from 'Open' to: 'Resolved'

Changed status from 'Open' to: 'Resolved'
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Reference: blender/blender#52152
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