The rendering result of hair is diffirent in the diffirent version!!! #66642

New Issue

Renesmee · 2019-07-10T04:33:23+02:00

Renesmee commented

2019-07-10 04:33:23 +02:00

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 417.01

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-10 10:48, hash: ac8c795429
Worked: (optional)

Short description of erroruntitled.7z
[Hi,there is a question.The rendering result of hair is diffirent in the diffirent version（Blender2.79 and Blender2.80）.I really hope you can fix this bug.Because many projects of Blender2.79 need to rendered in 2.80. But now we can’t because this bug. (T_T)]

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]

**System Information** Operating system: Windows-10-10.0.17763 64 Bits Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 417.01 **Blender Version** Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-10 10:48, hash: `ac8c795429` Worked: (optional) **Short description of error**[untitled.7z](https://archive.blender.org/developer/F7580348/untitled.7z) [Hi,there is a question.The rendering result of hair is diffirent in the diffirent version（Blender2.79 and Blender2.80）.I really hope you can fix this bug.Because many projects of Blender2.79 need to rendered in 2.80. But now we can’t because this bug. (T_T)] **Exact steps for others to reproduce the error** [Please describe the exact steps needed to reproduce the issue] [Based on the default startup or an attached .blend file (as simple as possible)]

Renesmee commented

2019-07-10 04:33:23 +02:00

Added subscriber: @xinku

Philipp Oeser commented

2019-07-10 08:06:41 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2019-07-10 08:06:41 +02:00

I assume this is because of the more efficient Russian roulette termination from cd023b6cec.
In above commit Min Bounces was removed.
It has been brought back though c9238e638f as Min Light Bounces / Min Transparent Bounces.

You can find these under Properties Editor > Render > Sampling > Advanced

Does setting this/these to something like Min Bounces in 2.79 give you a closer result?
(cannot render atm., but can check later, too...)

I assume this is because of the more efficient Russian roulette termination from cd023b6cec. In above commit `Min Bounces` was removed. It has been brought back though c9238e638f as `Min Light Bounces` / `Min Transparent Bounces`. You can find these under `Properties Editor` > `Render` > `Sampling` > `Advanced` Does setting this/these to something like `Min Bounces` in 2.79 give you a closer result? (cannot render atm., but can check later, too...)

Philipp Oeser commented

2019-07-10 10:52:38 +02:00

In #66642#716982, @lichtwerk wrote:
I assume this is because of the more efficient Russian roulette termination from cd023b6cec.
In above commit Min Bounces was removed.
It has been brought back though c9238e638f as Min Light Bounces / Min Transparent Bounces.

You can find these under Properties Editor > Render > Sampling > Advanced

Does setting this/these to something like Min Bounces in 2.79 give you a closer result?
(cannot render atm., but can check later, too...)

Forget about this comment, I now have it rendered and this is not the look, it is about the particle distribution...
Will confirm on first sight, checking...

> In #66642#716982, @lichtwerk wrote: > I assume this is because of the more efficient Russian roulette termination from cd023b6cec. > In above commit `Min Bounces` was removed. > It has been brought back though c9238e638f as `Min Light Bounces` / `Min Transparent Bounces`. > > You can find these under `Properties Editor` > `Render` > `Sampling` > `Advanced` > > Does setting this/these to something like `Min Bounces` in 2.79 give you a closer result? > (cannot render atm., but can check later, too...) Forget about this comment, I now have it rendered and this is not the look, it is about the particle distribution... Will confirm on first sight, checking...

Brecht Van Lommel commented

2019-07-10 11:38:58 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2019-07-10 11:38:58 +02:00

Note that the particle distribution random number generator was intentionally changed in 2.80.

Philipp Oeser commented

2019-07-10 19:17:55 +02:00

Made a couple of test (without looking at code -- it might very well be the RNG @brecht was talking about): seems like only interpolated children are affected, simple children with all kinds of randomness seem the same in 2.79 and 2.8.

Philipp Oeser commented

2019-07-10 19:22:48 +02:00

[which makes #63534 come to my mind -- might be unrelated though]

Renesmee commented

2019-07-12 10:10:54 +02:00

Note that the particle distribution random number generator was intentionally changed in 2.80.

Is there any solution? This problem has caused us a lot of trouble.

> Note that the particle distribution random number generator was intentionally changed in 2.80. Is there any solution? This problem has caused us a lot of trouble.

Brecht Van Lommel commented

2019-07-14 19:11:07 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2019-07-14 19:11:07 +02:00

Brecht Van Lommel self-assigned this 2019-07-14 19:11:07 +02:00

Brecht Van Lommel commented

2019-07-14 19:11:07 +02:00

No, there is no way to get the exact same result in 2.79 and 2.80 with child particles unfortunately. Further I can't see a bug here.

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The rendering result of hair is diffirent in the diffirent version!!! #66642