Light Bounces in 2.8 producing worse results #60867

New Issue

Jonathan Lax · 2019-01-25T17:03:02+01:00

Jonathan Lax commented

2019-01-25 17:03:02 +01:00

System Information
Operating system: OSX 10.13.6
Graphics card: AMD Radeon R9 M395X 4096 MB

Blender Version
Broken: 2.8 7f77961f1c

Rendering high quality stills of glass/liquids and glossy surfaces produces worse results in 2.8. Please see attached Scene file.

In 2.79, with Light bounces at 12max and 12min, I get a very clean usable render in 6 minutes.
In 2.8, with Light bounces at 12 (cannot set minimum), I get an unusable grainy render in 3 minutes.

If I up samples to clean up the 2.8 render so rendertime is closer to 6 minutes, the results are still grainy. Please allow me to change the light bounces to min/max in 2.8 as that is much more efficient and produces better results than not allowing a minimum amount.

I hope this is clear. To get similar results in Blender 2.8 requires nearly double the rendertime, but this can be avoided if minimum light bounces can be set to the same as max.

Exact steps for others to reproduce the error
Open file in Blender 2.79b Release. Hit render, log time to render and quality of image.
Open file in Blender 2.8 beta latest. Hit render, log time to render and poorer quality of image. Then set samples to 10x and you'll see rendertimes are now much much higher but image quality is still lower than 2.79. In 2.79 if you change min light bounces to 1, then a similar result and rendertime can be seen. So this is a light bounce issue. Please allow users to set minimum light bounces in 2.8 to fix and speed up renders.
Blender_BugReport_Jlax.blend

**System Information** Operating system: OSX 10.13.6 Graphics card: AMD Radeon R9 M395X 4096 MB **Blender Version** Broken: 2.8 7f77961f1c38 Rendering high quality stills of glass/liquids and glossy surfaces produces worse results in 2.8. Please see attached Scene file. In 2.79, with Light bounces at 12max and 12min, I get a very clean usable render in 6 minutes. In 2.8, with Light bounces at 12 (cannot set minimum), I get an unusable grainy render in 3 minutes. If I up samples to clean up the 2.8 render so rendertime is closer to 6 minutes, the results are still grainy. Please allow me to change the light bounces to min/max in 2.8 as that is much more efficient and produces better results than not allowing a minimum amount. I hope this is clear. To get similar results in Blender 2.8 requires nearly double the rendertime, but this can be avoided if minimum light bounces can be set to the same as max. **Exact steps for others to reproduce the error** Open file in Blender 2.79b Release. Hit render, log time to render and quality of image. Open file in Blender 2.8 beta latest. Hit render, log time to render and poorer quality of image. Then set samples to 10x and you'll see rendertimes are now much much higher but image quality is still lower than 2.79. In 2.79 if you change min light bounces to 1, then a similar result and rendertime can be seen. So this is a light bounce issue. Please allow users to set minimum light bounces in 2.8 to fix and speed up renders. [Blender_BugReport_Jlax.blend](https://archive.blender.org/developer/F6401227/Blender_BugReport_Jlax.blend)

Jonathan Lax commented

2019-01-25 17:03:02 +01:00

Added subscriber: @JonathanLax