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Where is black pixel filter setting at?

TheKDTheKD Posts: 2,696
edited January 2016 in Daz Studio Discussion

So I was doing a render, I looked at my log and see this a billion times:

 

WARNING: dzneuraymgr.cpp(261): Iray ERROR - module:category(IRAY:RENDER):   1.0   IRAY   rend error: Degraining filter cannot be combined with "black pixel filter".

 

I don't see any black pixel filter in the render settings anywhere to turn off. 

Post edited by TheKD on

Comments

  • ToborTobor Posts: 2,300

    The degrainer is the Noise Pixel Enable option. Turn that off. It's not needed if you aren't prematurely stopping the renders. The other types of pixel filtering cannot be turned off.

  • TheKDTheKD Posts: 2,696
    edited January 2016
    Tobor said:

    The degrainer is the Noise Pixel Enable option. Turn that off. It's not needed if you aren't prematurely stopping the renders. The other types of pixel filtering cannot be turned off.

    My render was stopping because of 99 converge according to the log, but was still grainy as hell. I think it was because of the mirror. If I got rid of the mirror, it rendered without all the grain. The reflection was part of the composition though, so I tried the grain filter. Why bother putting a grain filter in there, if it is conflicting with another filter you can't toggle off?

     

    Post edited by TheKD on
  • mjc1016mjc1016 Posts: 15,001
    TheKD said:
    Tobor said:

    The degrainer is the Noise Pixel Enable option. Turn that off. It's not needed if you aren't prematurely stopping the renders. The other types of pixel filtering cannot be turned off.

    My render was stopping because of 99 converge according to the log, but was still grainy as hell. I think it was because of the mirror. If I got rid of the mirror, it rendered without all the grain. The reflection was part of the composition though, so I tried the grain filter. Why bother putting a grain filter in there, if it is conflicting with another filter you can't toggle off?

     

    Just because a render hits 99% convergence doesn't mean it is 'done'...there are two other stop conditions, time and total number of iterations.  And at 99%, things like mirrors can still be 'noisy'.  To finish, you would need to overide things. so it san render longer.

  • TheKDTheKD Posts: 2,696

    I don't see a total number of iterations setting. Is that what max samples mean? I have mine set at 15000, I think default was 5000

  • mjc1016mjc1016 Posts: 15,001

    Yes, Max Samples should be the right one...

  • TheKDTheKD Posts: 2,696

    Ok, thanks. I remember cranking that up higher when I first started iray, and didn't see any difference. I will remember to try cranking that up next time I am getting grain, usually my inages are nice and clear on 15000 setting.

  • mjc1016mjc1016 Posts: 15,001

    You may need to bump other things, like the time limit (it defaults to two hours) up too.

    Also adjusting the amount of light (not lights) and tone mapping can have a dramatic impact on how long reflective surfaces take to clear up...and it isn't really something that is a 'formula', for PBR renderers I've used it seems to be more of 'play with it until you get it right' for highly reflective items.  A couple I've done in Luxrender, the 'fireflies' on from the chrome (it was a car with lots of chrome) eventually resolved into caustics...so that's something else to account for: relfective caustics.

  • TheKDTheKD Posts: 2,696
    edited January 2016

    Oh yeah, I have the time limit bumped up to 500,000 seconds lol. Caustics, hmmmm. Didn't even have that turned on, I thought that was more for liquids. Something else to think about. The PBR in mantra just seems to do everything right by default, I rarely ever had to mess with the settings much. Last render I did in mantra took me about 7 hours, but I was rendering at 10k x 8k pixels, and it had billions of polys after all the subdivision was kicked in. If I could get nice looking skin as fast as I could in Iray(meaning setup speed), I would not even bother with iray. I literaly spent weeks trying to get skin looking good in mantra, then iray came out and I gave it a try. Was blown away by the results, no tweaking this, tweaking that, test renders for a week, just render lol. I mean when the point of the render is the scene, and people ar rendered far away, mantra looks great. But for closeups, where the humans are the subject, it takes forever to get even passable results. Always tweaking the SSS settings and stuff. 

    Post edited by TheKD on
  • ToborTobor Posts: 2,300

    Ah, well... Even the nVidia technical docs are obtuse about how the degrainer works, and as Daz doesn't provide any documentation of their own, we are left to guessin,  and way too many hours needlessly experimenting when we should be making art.

    Anyway, the degrainer filter is intended for when you plan on "short sheeting" Iray by intentionally not allowing it to reach full pixel convergence, maybe on the order of 30-50%. After that, it won't have much effect, which is why you found it doesn't really help in cleaning up the graininess of a full render.

    If you are getting too much grain, the likely culprit is not enough light. Convergence estimates are based on a certain number of ray hits touching upon the same pixels. Less light in a scene means fewer ray hits; fewer ray hits means slower (or even incomplete) convergence.

    You don't have to sacrifice your image dynamics by increasing the light levels in your scene. This is what Tone Mapping is for. Suppose you need to double or even quadruple the intensities of the light in your scene. This will cause the scene to be over-exposed, so you knock the f-stop (or shutter speed or ISO) down 2 or 3 stops to compensate.

    Some lighting conditions cause grain even if the light source is increased to sunlight levels. Iray has the most difficulty with indirect lighting. The architectural sampler filter is designed as a way to provide a "hint" to Iray that the lighting in a scene is indirect. 

  • ToborTobor Posts: 2,300
    TheKD said:

    My render was stopping because of 99 converge according to the log, but was still grainy as hell. I think it was because of the mirror. If I got rid of the mirror, it rendered without all the grain. The reflection was part of the composition though, so I tried the grain filter. Why bother putting a grain filter in there, if it is conflicting with another filter you can't toggle off?

    When mirrors cause overly long renders, try reducing Max Ray Path from -1 (infinite) to maybe 6-8. Don't go much below that, or some surfaces, such as eyes, may not render properly. By reducing the number of ray paths, you simplify the calculations that Iray must do in scene with a heavy amount of reflections.

     

  • mjc1016mjc1016 Posts: 15,001
    Tobor said:

    When mirrors cause overly long renders, try reducing Max Ray Path from -1 (infinite) to maybe 6-8.

    Funny in 3DL you start low and work up on the rays...but most PBRs you start cutting back on the.  Which makes sense...it is introducing a bias by cutting the paths...simplified paths aren't 'real'.   And while the theoretical maximum is that a light ray will bounce around until it bounces out of 'view' or gets absorbed by something, in real life they aren't quite that long lasting or we just can't see them any longer because they are below the threshold ours work at.  And yes, renderers will continue to calculate them, even if we wouldn't be able to see them...unless you cut them off...and that's what turning down the Max Ray Path does.  And 6 or 8 is about the minimum for good glass and eye surfaces...

    As to not having the caustic sampler on...a couple of times I've played with it (a couple of gemstone renders) there were some very interesting results.  One thing I did notice is with it off, sometimes if there is going to be something in a particular spot, it may be a firefly haven that will take forever to clear...so some cases it may be faster to have it on, although most of the time, turning it on is only advised when you absolutely need it.  And reflective caustics can be as much of pain/time eater as the transmitted ones.

  • sfaa69sfaa69 Posts: 353

    Apparently if you set the time to zero seconds, it takes that out of the equation. One less thing to think about.

  • sfaa69sfaa69 Posts: 353

    Is there a place where you can find out what each of the settings do? I haven't found one yet. Max Ray path? Since it takes so long to render, trial and error doesn't seem to be a good answer.

  • mjc1016mjc1016 Posts: 15,001

    The Nvidia docs...

    http://www.migenius.com/doc/realityserver/latest/resources/general/iray/manual/index.html#/concept/preface.html

    http://www.nvidia-arc.com/products/iray/technical-documentation.html

     

    Sickleyield has a guide, but it is a little out of date, as it was done when Iray first came out.

    http://sickleyield.deviantart.com/journal/Tutorial-Getting-Started-With-Iray-519725115

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