iRay Noise on opacity/cut out areas
Wallace3D
Posts: 170
Is anyone else showing noise on areas that are supposed to be fully transparent?
For example a Shirt worn by Genesis 3 Male and the sleeves are set to CUT OUT 0% and the area where the sleeves are you can still see it but as transparent noise.
I have turned off any glossiness and tried every setting with just opacity/cutout setting to 0% and no matter what I see this noise
I even see it on the transparent areas of Hair.
This is on Beta 4.9.3.128
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Comments
Do you have any refraction turned on (weight > 0)?
Hi,
OK
On 4.9.2.70 (the regular one) you only have to render long enough ( >99% convergement).
The noise still shows up after 100% render at 7500 samples and depending on the ligthing it can be more visible than ever
this is a simple test scene where (on a 4K Monitor) it is clearly visible (some may not see it as I never noticed it until i got the new monitors)
First Image is the setup with the sleeves cut off at 0% you can see the noise where the sleeve is on the arm
the second image is the sleeve visibility turned off and nothing else changed. as you can see the noise is gone.
You still have some noise at the middle finger, as you look close.
Could you please show your render settings (parameter: Progressive Render)?
Cutout opacity does not mean it's invisible to Iray. Iray is still rendering with, or through, the material. The rendering engine knows the surface is there, and the other remnant settings of the shader are still an influence..
As you've found, if you're getting noise or any other artifact, the better approach is to hide the surface, not just set its opacity to 0. This way the polygons of the hidden object are not part of the scene. As needed you can also try using the Geometry Editor and hide the visibility of polygons of anything you want to actually be gonesville from the scene. I believe this has the same effect as turning the eyeball on and off in the Scene list.
In this case, it may be a simple matter to click on eyeball of the surface zone in the Geometry Editor Tool Settings. However, if you want to hide polygons that are only part of one or more surfaces, after selecting them with the Geometry Editor Tool, you should create a new surface and assign those polygons to it. Then click on the eyeball for your new surface to hide them. I found out the hard way, just hiding selected polygons only works until you close the scene.
Hi Tobor,
as you may have a closer look to the clothing, hiding the sleeves is only possible (and that way implemented by the product owner) by setting opacity to ZERO.
Yes, of cause the render engine knows that the material is still there. But opacity = 0 is absolutely transparent as if there isn't any material. Contary to transparency build by refraction (i.e. glass or water).
We all know, that nVidia still has many bugs in their render engine. And this seem to be a new one, if other users can reproduce this effect.
But we still don't know enough about the individual conditions in the scene of "Wallace3D".
I own several clothings of the good old 3Delight times with segments hidden by opacity. Up to now I didn't get these grainy artefact if only I render long enough (>99% converged).
Using the Geometry Editor ANY polygons in ANY mesh can be hidden without touching the opacity of the surface. And when they are hidden, it's like Tobor said...
If the creator of the item didn't include groups or surfaces, it would require selecting the actual polygons to hide as opposed to a group or surface. As a creator I can't cover every option that everyone would ever possibly want, the best I can do is have some options and then let the end user customize to their needs. That's what the purpose of the Geometry Editor is.
Also another area to look at...the map itself. It should be a greyscale (mode set in image editor) map with no embedded color profiles (setting to greyscale should discard any profiles). RGB maps hould not be used as control maps and embedding color profiles in a control map is just going to compound any problems.
Cutout Opacity = 0% does NOT mean 'as if there isn't any material' at all. It means that "...in the absence of other effects of the shader, the material contributes no color to the scene.'
Other layers in the shader, top coats, IOR not zero, specular reflections, and many other parts of the shader (depending on how it is written) may not use the cutout opacity parameter the same way. Cutout Opacity in Iray is NOT the same as 'transparency' in 3DL.
Make sure that the other parts of the shader are set so that it cannot affect the image. Roughness needs to be 0, IOR needs to be 1.0, Refraction weight needs to be 0, Top Coat weight needs to be 0, etc.
Also, ANY transmaps will slow down rendering, even when the above is taken into account. This is because the algorithms cannot know ahead of time whether or not it's all or nothing. So expect the render passes in Iray to be slower.
As MJC said, make sure the map is greyscale and proper bit-depth, too. And don't use jpg files (or any file which uses lossy compression) for transmaps, as the lossy compression artifacts can result in slight noise in the image itself even if the map looks pure white/black.
Absolutely correct. Even with Cutout Opacity to 0, the shader is still active, and Iray processes the entirety of the shader block. Setting Cutout Opacity to 0 does not cause Iray to ignore the material. Because of this, rendering can be prolonged, espectially considering other shader effects that Iray must calculate before it's been told the material is cut out. Prolonging rendering introduces the potential for undersampled pixels.
This is a misconception stated early on with some users and has never been corrected.
If a mesh is there, it will get shipped to the scene database. One way or another, Iray will try to shade it. It may come out as invisible, but it was still processed. The only way to make something completely invisible to Iray, and entirely skip processing through a shader applied to it, is to remove that object (or its polygons) from the scene.
Well, I suppose one COULD make a 'null' shader to apply, but that wouldn't help THIS particular instance....but if a single node had multiple material zones and you wanted to make one(or more) of them 'vanish', having such a 'null' shader could be useful.
Note, it still has to be calculated, it would simply have no parameters, and would act as a completely diffuse surface with no specularity, no reflection, no refraction, and a fixed cutout opacity of 0. Wouldn't be too hard of a utility shader to make......
An actual MDL shader set up for this would be pretty quick, and wouldn't slow rendering down very much.
Yes, you'd have to do this on the MDL level because the Uber shader still has that large network, and that's what you'd want to avoid. You could always start from one of the nVidia Example shaders, since those are much simpler to begin with.
Even so, I bet all of 14 people in the planet would use it, because of the steps involved to install the thing. Ideally Daz should include it in some future build. Then, these sorts of threads would be much shorter!
I think 3 of the 14 have answered this thread...
Having the same issue too with the 4.9.3.128. No issue with 4.9.2. so far. What ever reason it is, I think this should fixed.
Try making a full black .jpg (RGB 0/0/0) and adding it to the Cutout channel. (It can be any size - I use 512x512). This solved another weird cutout issue for me.
It's still there in 4.9.3.153.