Refraction BSDF Renders Slower With Extreme Edges? #42701

New Issue

Zauber Paracelsus · 2014-11-23T16:51:23+01:00

Zauber Paracelsus commented

2014-11-23 16:51:23 +01:00

System Information
OS: Ubuntu 14.04, Kernel 3.13.0-39
CPU: AMD Phenom II 970 Deneb quad-core
GPU: GTX 650 Ti, driver version 331

Blender Version
Broken: 2.72 dev, hash c6ab67b

Short description of error
With extreme edges on certain objects, the Refraction BSDF appears to take much longer to render, typically taking an order of magnitude or so longer to render on the affected render tiles. It occurs in both CPU mode and GPU mode and when using Path Tracing or Branched Path Tracing, but is much more extreme when using GPU mode.

Only certain shapes seem to expose the issue, and of the default primitive shapes, it is reproduced most readily by the torus and monkey shapes (more so with the monkey). Other shaders do not appear to have this problem, not even the Glass BSDF (which includes its own refraction effect).

Exact steps for others to reproduce the error
The blend file below demonstrates the problem. Hit render, and note the time. Then set the Refraction BSDF's roughness to 0, and render again. Compare the render times.

Refraction_Bug_Test.blend

**System Information** OS: Ubuntu 14.04, Kernel 3.13.0-39 CPU: AMD Phenom II 970 Deneb quad-core GPU: GTX 650 Ti, driver version 331 **Blender Version** Broken: 2.72 dev, hash c6ab67b **Short description of error** With extreme edges on certain objects, the Refraction BSDF appears to take much longer to render, typically taking an order of magnitude or so longer to render on the affected render tiles. It occurs in both CPU mode and GPU mode and when using Path Tracing or Branched Path Tracing, but is much more extreme when using GPU mode. Only certain shapes seem to expose the issue, and of the default primitive shapes, it is reproduced most readily by the torus and monkey shapes (more so with the monkey). Other shaders do **not** appear to have this problem, not even the Glass BSDF (which includes its own refraction effect). **Exact steps for others to reproduce the error** The blend file below demonstrates the problem. Hit render, and note the time. Then set the Refraction BSDF's roughness to 0, and render again. Compare the render times. [Refraction_Bug_Test.blend](https://archive.blender.org/developer/F125577/Refraction_Bug_Test.blend)

Zauber Paracelsus commented

2014-11-23 16:51:23 +01:00

Changed status to: 'Open'

Zauber Paracelsus commented

2014-11-23 16:51:23 +01:00

Added subscriber: @ZauberParacelsus

Thomas Dinges commented

2014-11-24 06:45:54 +01:00

Changed status from 'Open' to: 'Archived'

Thomas Dinges closed this issue

2014-11-24 06:45:54 +01:00

Thomas Dinges self-assigned this 2014-11-24 06:45:54 +01:00

Thomas Dinges commented

2014-11-24 06:45:54 +01:00

We had a similar bug report a few weeks ago: https://developer.blender.org/T41633 You can find further info here.

Long story short: Render time with a refraction shader is expected to be higher, than with a Glass shader.

We had a similar bug report a few weeks ago: https://developer.blender.org/T41633 You can find further info here. Long story short: Render time with a refraction shader is expected to be higher, than with a Glass shader.

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Refraction BSDF Renders Slower With Extreme Edges? #42701