Grainy Iray renders

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  • One other thing I noticed is, if I use the architectural sampler, together with the bloom filter, the bloom changes dramatically. It fills up the picture. I was taking to much time to figure out the right settings using both filters together, so I just gave up on that one.

  • FishtalesFishtales Posts: 6,208
    edited September 2015

    The way I would try it would be to turn Environment off so that it isn't giving any light to the scene. I would then set the candles to real time settings, I think that is 5 watts at 0.5 efficacy but I can't remember at the moment and temp of 1850K, and then set the Tone Mapping camera to get the feel I want. Then bring in the Environment and keep decreasing the light output until the scene is back to my original. I will also try and balance the Tone Mapping camera and the environment lighting until the scene looks right and then try some test renders still only using the Tone Mapping and environment lighting to change the scene. The candle light is the main point of interest so the scene has to be set up for them and once set shouldn't be touched unless really necessary.

    Post edited by Fishtales on
  • Oso3DOso3D Posts: 15,085

    I would highly suggest making a brighter, more evenly lit scene with good light, and then darkening it to your liking in post.

    Renderers like having good light, and it's easier to loose brightness than try to go back up.

     

  • I would highly suggest making a brighter, more evenly lit scene with good light, and then darkening it to your liking in post.

    Renderers like having good light, and it's easier to loose brightness than try to go back up.

     

    Post darkening lowering the exposure?

  • Oso3DOso3D Posts: 15,085

    Yes. It will then render more quickly, and you have a more fine ability to dial in to the effect you want.

     

  • ToborTobor Posts: 2,300
    Ralf1958 said:

    I have this picture, by example, the lower part of the pumpkin and the candle is grainy. I am trying to get rid of it but... no luck. The scene is lit only by the candles and the environment is set very low at 0.02. I don't want to encrease or add more lights, I want it to be dark. If I encrease the tone mapping like ISO or exposure, like someone suggested, it gets to bright. So, how would you guys manage this?

    Actually, I think it looks pretty good -- the noise in the darker areas add a spooky texture.

    The idea behind upping the illumination is to give the Iray more light to work with. You then *decrease* the brightness in the tone mapping. For example, if you double the light in the scene, choose an f/stop that is one higher -- f/8 to f/11, for example.

    Think of tone mapping as Photoshopping your render, without Photoshop. There are no photographers on the planet that can make a perfect picture each time. The really great photos are retouched -- the most famous Ansel Adams black and white photos were made in the darkroom. You're doing the same here. You're adjusting the scene light levels to give Iray more "photons" to work with, then using the various tone mapping controls to bring it back to where you want.

  • After many different tests, I got crystal clear dark renders with very low light, using the "architectural sampler". Renders take pretty long, for a 1920x1080px, something like two days, but the results are very good. In "progressive rendering" I pulled up the Max samples "way over the top" at 150.000!!! Just to make sure the render doesn't stop to early. Did the same thing with the Max Render Time at 2.592.000 wich is equivalent to 30 days. I also tyed the combination of architectural sampler and bloom filter but that is very, very time consuming, this really takes forever! I actually never got to complete a dark render with this combination. In one test, the machine was running for over 6 days and it was still not done. The result was good, probably excellent if I would have waited until the end... well, it was at 95%... but i didn't wanted to wait any longer, it was just a test. My computer: Intel Core i7-4771 CPU @ 3.50 GHz 16GB RAM nVidia GeForce GTX 970. Rendered on GPU. I am rendering an image right now that should be done soon. I will post it here once ready.

  • HavosHavos Posts: 5,573
    Ralf1958 said:

    I have this picture, by example, the lower part of the pumpkin and the candle is grainy. I am trying to get rid of it but... no luck. The scene is lit only by the candles and the environment is set very low at 0.02. I don't want to encrease or add more lights, I want it to be dark. If I encrease the tone mapping like ISO or exposure, like someone suggested, it gets to bright. So, how would you guys manage this?

    One option would be to render the candle in a separate render with a bit more light, and then use post work to put the non-grainy candle surface only into the main image, dimming the relevant layer to merge better with the rest of the image. Not ideal, and a some what awkward solution, but should work.

  • Havos said:
    Ralf1958 said:

    I have this picture, by example, the lower part of the pumpkin and the candle is grainy. I am trying to get rid of it but... no luck. The scene is lit only by the candles and the environment is set very low at 0.02. I don't want to encrease or add more lights, I want it to be dark. If I encrease the tone mapping like ISO or exposure, like someone suggested, it gets to bright. So, how would you guys manage this?

    One option would be to render the candle in a separate render with a bit more light, and then use post work to put the non-grainy candle surface only into the main image, dimming the relevant layer to merge better with the rest of the image. Not ideal, and a some what awkward solution, but should work.

    Oh... sorry! I wasn't talking about that pumpkin and candle render anymore. By the way I got a very good result on that one as well with the architectural sampler. :-) I'm on to another render right now, it's turning out really, really nice.

  • ToborTobor Posts: 2,300

    The architectural sampler is designed primarily for  indirect lighting, which often has the kind of soft shadow detail that causes the slow convergence. It does work by employing some "cheats" in how Iray processes the scene, but if the end result is what looks good that's all that matters.

    From nVidia's programmer's documentation: "The Iray Photoreal architectural sampler can be used to improve the convergence speed of difficult scenes, as such complicated lighting scenarios can then be handled much more efficiently with this sampler. A common scene type that profits from this specialized sampler is indoor architectural visualization, especially if it is mostly illuminated by indirect lighting. One specific example would be a room that is illuminated by light sources placed in neighboring rooms or by outdoor lighting (such as the Sun and Sky model) shining through a small window. As the sampler introduces additional overhead and also only works well when a lot of iterations need to be spent on finalizing the picture it should be avoided for rather simple scenes, or in general mostly directly lit scenes such as outdoor or design visualization."

  • Well, here is the final render... it only took 24 hours... :-) I'm pretty happy with it.

    Disco 01.jpg
    1920 x 1080 - 1M
  • Ralf1958 said:

    Well, here is the final render... it only took 24 hours... :-) I'm pretty happy with it.

    Very nice!

     

  • ronmolina said:
    Ralf1958 said:

    Well, here is the final render... it only took 24 hours... :-) I'm pretty happy with it.

    Very nice!

     

    Thanks :-) It's a reconstuction of a discotheque on the Garda lake (Italy) from back in 1978. Memories of good times, old pictures helped a lot to recreate the original atmosphere... :-)

  • So I've gone through the thread here, and my takeaway from it is this; if I'm wrong or missed something, someone please shout:

    Set render quality to 3

    Set samples to a ludicrously high number

    Set the timeout to something greater than 2 hours, anywhere up to several days (as calculated in seconds)

    If I'm reading correctly, and assuming all illuminated surfaces are Iray in one way or another and adequately lighted … this combination will go a long way toward eliminating grain and noise, yes?

  • mjc1016mjc1016 Posts: 15,001

    So I've gone through the thread here, and my takeaway from it is this; if I'm wrong or missed something, someone please shout:

    Set render quality to 3

    Set samples to a ludicrously high number

    Set the timeout to something greater than 2 hours, anywhere up to several days (as calculated in seconds)

    If I'm reading correctly, and assuming all illuminated surfaces are Iray in one way or another and adequately lighted … this combination will go a long way toward eliminating grain and noise, yes?

    Yes.  The key thing is to have the 'stop' conditions set to high enough/long enough for the render to actually finish.  The stop conditions do not mean that the render has actually 'finished' to a degree that it is usable for anything.   Many renders won't finish with default stop conditions, if not done with a large memory video card that is utilizing the GPU to render, so for CPU rendering they will need to be adjusted.

  • fastbike1fastbike1 Posts: 4,078

    I think it's in the eye of the beholder. I rarely see the "grain" in the renders that the "grainers" complain about. REmind me of the pixel peepers in digital photography that obsess about noise when they blow the image up beyond 100%.

    I render with the default settings for almost everything and don't get grainy images with proper lighting (which doesn't necessarily mean bright). I have over 40 years of photography experience and I know what grain and noise look like.

  • RafmerRafmer Posts: 564

    Also, if you don't want to mess with progressive render settings, there is a preset option tab in render settings with an advanced setup for decent quality renders, it also enables the noise filter with good-to-go settings.

  • fastbike1 said:

    I think it's in the eye of the beholder. I rarely see the "grain" in the renders that the "grainers" complain about. REmind me of the pixel peepers in digital photography that obsess about noise when they blow the image up beyond 100%.

    I render with the default settings for almost everything and don't get grainy images with proper lighting (which doesn't necessarily mean bright). I have over 40 years of photography experience and I know what grain and noise look like.

    Well good for you.

  • mjc1016 said:

    Yes.  The key thing is to have the 'stop' conditions set to high enough/long enough for the render to actually finish.  The stop conditions do not mean that the render has actually 'finished' to a degree that it is usable for anything.   Many renders won't finish with default stop conditions, if not done with a large memory video card that is utilizing the GPU to render, so for CPU rendering they will need to be adjusted.

    Ah, now it becomes a bit clearer. I'm using relatively off the shelf hardware, and I know the graphics cards in it share memory with the main machine's architecture; they're not particularly fancy or high-end. So it would make sense that, given the graphics limitations, things look a bit … funky at the default settings.

  • mjc1016mjc1016 Posts: 15,001

    Right...and since the graphics is sharing memory, it's likely to be an 'onboard' solution, not a dedicated card, which pretty much limits to a CPU only render...which will automatically mean longer render times.

  • Ralf1958 said:
    ronmolina said:
    Ralf1958 said:

    Well, here is the final render... it only took 24 hours... :-) I'm pretty happy with it.

    Very nice!

     

    Thanks :-) It's a reconstuction of a discotheque on the Garda lake (Italy) from back in 1978. Memories of good times, old pictures helped a lot to recreate the original atmosphere... :-)

    You going to package that set for the world??? That is awesome!

  • L'AdairL'Adair Posts: 9,479

    So I've gone through the thread here, and my takeaway from it is this; if I'm wrong or missed something, someone please shout:

    Set render quality to 3

    Set samples to a ludicrously high number

    Set the timeout to something greater than 2 hours, anywhere up to several days (as calculated in seconds)

    If I'm reading correctly, and assuming all illuminated surfaces are Iray in one way or another and adequately lighted … this combination will go a long way toward eliminating grain and noise, yes?

    Like so many others here, I do not have an Nvidia graphics card. In fact, I'm working with onboard graphics, which shares my 16GB of ram with the system. All my renders are CPU Only. I am, however, a "recovering perfectionist" and struggle with the concept of "good enough" in my renders. I have been known to let an image render for days to reach 100% convergence.

    I seldom set Quality higher than 1. (Though when I do, it's for something specific, like toning down the gloss in hair, or bringing out the details in reflections.)

    I use the following settings to prevent the render from stopping automatically before 100% convergence:

    Max Samples: 15000 (This is the high limit, which can be changed in Parameters, but I've yet to max out at 15000.)
    Max Time: 0 (Setting the time to 0 effective "turns off" this condition, allowing the image to render until one of the other two conditions are met.)
    Rendering Converged Ratio: 100%

    You can set Quality to a higher value, and it will take a higher number of samples to reach the Rendering Converged Ratio. But it will stop if the Max Samples value is reached; or the Max Time, if you don't set the value to 0.

     

  • L'Adair said:

    So I've gone through the thread here, and my takeaway from it is this; if I'm wrong or missed something, someone please shout:

    Set render quality to 3

    Set samples to a ludicrously high number

    Set the timeout to something greater than 2 hours, anywhere up to several days (as calculated in seconds)

    If I'm reading correctly, and assuming all illuminated surfaces are Iray in one way or another and adequately lighted … this combination will go a long way toward eliminating grain and noise, yes?

    Like so many others here, I do not have an Nvidia graphics card. In fact, I'm working with onboard graphics, which shares my 16GB of ram with the system. All my renders are CPU Only. I am, however, a "recovering perfectionist" and struggle with the concept of "good enough" in my renders. I have been known to let an image render for days to reach 100% convergence.

    I seldom set Quality higher than 1. (Though when I do, it's for something specific, like toning down the gloss in hair, or bringing out the details in reflections.)

    I use the following settings to prevent the render from stopping automatically before 100% convergence:

    Max Samples: 15000 (This is the high limit, which can be changed in Parameters, but I've yet to max out at 15000.)
    Max Time: 0 (Setting the time to 0 effective "turns off" this condition, allowing the image to render until one of the other two conditions are met.)
    Rendering Converged Ratio: 100%

    You can set Quality to a higher value, and it will take a higher number of samples to reach the Rendering Converged Ratio. But it will stop if the Max Samples value is reached; or the Max Time, if you don't set the value to 0.

    I recently read you don't want to go past 99% for convergiance ratio, something about a bug and the software crashing often if you do.

    Target resolution here is usually important as well, which can effect the time also.  That said many of my renders take about 24-30 hours to run using the following:

    Resolution 2560x1440

    Convergiance ratio 99%

    Min Samples 10

    Max Samples 20000-25000 

    Render Quality 2

    Most scenes, have several emesive surfaces, and yes these I have found signifigantly increase render time, usually I try and convert the 'lights' in many scenes into real lights so they look natural. 

    In fact, Iray based shaders and surfaces increase the time signifigantly, however they look so good I don't care!!!  Items like Glass, Water which before just looked fake, respond wonderfully.

    Hardware: Single GTX 970.

    Now if I can figure out my own lighting issues.

  • DkgooseDkgoose Posts: 1,451

    So how high would be too high for render quality? I didn't even realize there was an option till today lol

  • Oso3DOso3D Posts: 15,085
    I have found that most of my issues about how Iray renders look (small scale soft/blurriness) are handle easily with Sharpen tool in post. Sharpen 40-60 in GIMP makes for crisp images 99% of the time, and is way less trouble than ramping up render times.
  • DkgooseDkgoose Posts: 1,451

    I got the skies of iradience and the night skies result in extremely grainy renders and i read here about the render quality possibly helping so thought maybe cranking up the dial would lead to a much better image 

  • Ralf1958Ralf1958 Posts: 688
    jas_va_26 said:
    Ralf1958 said:
    ronmolina said:
    Ralf1958 said:

    Well, here is the final render... it only took 24 hours... :-) I'm pretty happy with it.

    Very nice!

     

    Thanks :-) It's a reconstuction of a discotheque on the Garda lake (Italy) from back in 1978. Memories of good times, old pictures helped a lot to recreate the original atmosphere... :-)

    You going to package that set for the world??? That is awesome!

    Well... maybe one day smiley When I get some spare time to reorder all the files. That project is not very well organized... some files here and there all over my harddrive... smiley

  • JohannaJohanna Posts: 119
    edited January 2016

    As a professional photographer i can say: Its always a good idea to do a test render of a very small area (your main focus area, like face / eyes)

    In times of digital imaging we are used to have a result on click and now. 3D work nowadays is more like the old chemical photography process.

     

    We can compare this 3D work to the workflow in a professional photostudio in the 1980s.

    Developing a Kodak E6 film was very expensive and took like 3-5 hours to see a result.

    Thats why we took (very expensive also) professional Polaroids up front to judge the light and after a few of them we took the final shot.

     

    A little test render need like 1-2 hours i.e.

    If this test render looks great its worth to start a 20 hours rendering with no frustration at all.

     

    Hugs to all, LIVA 

    Post edited by Johanna on
  • MiraaMiraa Posts: 13

    None of them worked for me. Look.

    I have done every settings. HELP.sad

    Healing04.png
    970 x 545 - 955K
  • MiraaMiraa Posts: 13

    None of them worked for me. Look.

    I have done every settings. HELP.sad

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