iRay suddenly very grainy....possible bug?
PA_ThePhilosopher
Posts: 1,039
Hey guys,
So I just opened a scene I was working on yesterday, and for some reason, iRay is now rendering very grainy. Normally on my GTX 780 Ti, the grains are gone within seconds. Now the noise is not going away at all. I have made no changes since Yesterday, other than running an overnight animation render. This is what I've tried;
1. resetting to defaults in render settings
2. creating a new scene with a simple plane and point light (see photo below)
3. making sure my 780 Ti is checked in render settings
Any ideas what the issue may be?
Thanks,
Davide
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Comments
Here is a render out to 500 iterations.
Normally, the grain should be gone within a few iterations.
Strange.
It would help to know your Tone mapping and environment (from Render Settings) and light parameter settings.
Everything is default (I reset to defaults). In the scene above, I created a brand new file, then switched to "Scene only." That is the only change I made to the settings. I added a point light and two planes.
After doing more testing, it appears this artifact only occurs when an object is reflected on a surface. When there is no reflection, then I get no noise at all; everything is smooth again. Here is another example of a simple emissive surface and a couple primitives;
Why is the only changed setting gamma? And what was it's default value (1 or 2.20)? And yes, even a tiny change from 1.0 to 0.99 could affect things dramatically.
Can someone please download this test scene and render it on their PC to see if this noise still exists?
The test file should be set to render to 300 iterations.
Here is what mine looks like;
Dang it. I can't attach a .tar file for some reason...
mjc,
The gamma does not matter, even if I change it back to default. The noise is still there.
Have you tried raising the film ISO or lowering the Shutter speed? The default tone mapping is for an outdoor scene in sunlight, which clearly doesn't match the lighting in your scene.
Hey guys,
I need your help. If you have a spare moment, can you please download the small test scene at ***this link,*** and render it to 300 samples and post your images?
I am having a problem with grainyness / noise in iRay, as you can see in my render below (@300 samples). This problem started with my computer on June 19th, the day after the latest version of Daz was released. Prior to that day, this problem did not exist.
I am still trying to figure out whether the issue is specific to my computer, or whether it is common to all Daz users...hence the purpose of this thread. If you can take a few moments to render this for me and post your results, I would be greatly appreciative.
Davide
Richard,
Thanks for the suggestions. I have tried all that however. I have moved every slider in every setting possible, and pushed every button. I have also tried changing every preference in the interface.
On a brighter note, I did figure out a way to upload my test scene, so other Daz users can download it and verify whether this problem also exists on other machines. Here is thread, for anyone who would be willing to help me out with this; http://www.daz3d.com/forums/discussion/58693/
Thanks again for all your suggestions thus far,
Davide
This is what I get.
I had a quick look and got the same result but dont know what you are trying to do, Changing some settings like scene only to dome and scene gets rid of the grain but completely changes the scene
Threads merged - please don't start a new thread on an existing topic.
300 iterations is very low - the default value is 5,000. Why are you setting it down there?
What happened to my attached image when you merged threads? It is no longer attached to my post.
Because I have been working at 300 iterations without any issues prior to June 19th.
Those who are familiar with iRay, know that it renders very clear very quickly, far below 100 iterations.
At 300 iterations, the image was often just as sharp as a final render. Now, not the case anymore.
The test scene is purposely low-lit to accentuate the issue. But the noise seems to be present everywhere now, in all my scenes. If you have a moment, please download the test scene I made at ***this link,*** and render it to 300 samples to compare with my version above. That would be appreciated.
If other members are getting the same noise, then it suggests a software issue, likely from the latest update on June 18th.
Davide
If that is so then the oddity is that it was rendering without noise before. Are you sure the settings for light source didn't change? It is going to take a while to converge - even letting it run for more iterations (currently at 2,500 with a slower shutter and higher ISO and still a lot of grain) but with only a single light source that's not surprising.
I am sure.
Below is a one-to-one comparison. The first render was done on June 18th (to 300 iterations). The second render was done a few days later (also to 300 iterations). There were no changes made to the scene. If you click on the second image, you will see the grain more clearly (notice the cheeks and reflections in the eyes).
I suspect the latest build released on June 18th is to blame....
If you have access to an older build of 4.8, I would like to try installing it to see if the issues resolves itself.
It is also interesting to note from the above comparison that iRay is rendering the two images differently. If you click on the first image, you will see that the face is slightly transparent. As the iterations on that render increase beyond 300, the transparency disappears. This was prior to June 19th.
In the second image, the face is totally opaque, but now with the introduction of the noise.
So it seems the calculations/processes that iRay used between these two renders is entirely different.
This leads me to conclude that its not just a matter of more or less iterations. Something significant happened ~June 19 that I have yet to account for.
Davide
The camera has also changed, unless those are manual crops. But I meant are you sure that there wasn't a change in settings as a result of a change in DS, not did you change anything.
That is a good question. I was hoping *you* might know the answer to that, as I don't have a record of all the settings that were in place prior to the recent update. If we can somehow get access to them, then I would be able to cross-reference them to the present settings in Daz, to see if release 8.4.0.59 changed anything.
This would be huge, actually....It may mean a simple fix in settings.
Davide
Have you tried it without tonemapping enabled?
Would you happen to have a render of this test scene with and without the noise? I have Studio versions 4.8.0.56 and 4.8.0.59 installed and I'm seeing the same results for both.
From what I can tell, this is a lighting issue.Plane 2 is emissive and is very bright and very small.Removing it seems to remove the noise.
If Plane 2 is the problem...check to see if it is set to double-sided. Szark had a post about double sided emitters really increasing render times.