Blocky Shadows from HDRI

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  • SevrinSevrin Posts: 6,306

    melissastjames said:

    j cade said:

    Anim said:

    Here is an example with "sunny_vondelpark_16k.hdr" from hdrihaven. With this one I can reproduce the issue every time. And it seems nothing on the ubershader side can solve it (only setting backscattering to a high value helps but that of course is not suitable in most cases). The same scene with a less intense hdr is ok. The waveforms show the range difference.

    I'm not sure about melissajames image, but yours is 100% a shadow terminator issue. And it has been making me sad for years, just about the only thing you can do is up the subdivisions. I've actually asked the iray devs about it on their blog, and they know about it and are working on things to improve it, though there's no timeline afaik.

    It seems as though my original attachment has been removed (not sure why). In my case, I upped the SubD to 2 on the clothing in question and it made no difference. And even with turning spectral rendering on, I still ended up with some jaggies in the final image that needed to be cleaned up in post.  

    The attachment is still there.  IDK why they're not always visible, but it wasn't removed. 

  • AnimAnim Posts: 241

    melissastjames said:

    ... The only HDRI in the pack that has given me grief is the first one. ...

     I don't have that pack but which image do you mean by "the first one". Is it shown in the promo page?

  • MelissaGTMelissaGT Posts: 2,611
    edited March 2021

    Anim said:

    melissastjames said:

    ... The only HDRI in the pack that has given me grief is the first one. ...

     I don't have that pack but which image do you mean by "the first one". Is it shown in the promo page?

    I'm not sure if any of the artistic promos use that one specific one. It's the first one on the upper left in my attachment. None of the other ones have this issue...and they're all high contrast. And when the issue does arise, I've only noticed it effect clothing...not skin or architecture. 

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  • AnimAnim Posts: 241

    Just noticed the issue can be triggered with normal lights as well.

    It is not specific to environments. Seems so, if contrasty light hits surfaces at unfavorable angles the shadow issue happens (@j cade - thanks for the hint). Googling reveald it is a common issue in rendering. There is a parameter "Shadow Terminator Offset" in iray which tries to solve it but it is not available in Studio.

    Attached are examples with spot lights - one with them set to point the other with sphere. I think it is the same with HDRIs. If they include a bright spot it can create those artifacts. Seems so, there is nothing that can solve this. Workaround would be to have more even light and do the rest in post. And, - again as j cade wrote - increase subd to make it less obvious (it will still be there but maybe not visible from a distance).

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  • AnimAnim Posts: 241
    edited March 2021

    melissastjames said:

    ... they're all high contrast. And when the issue does arise, I've only noticed it effect clothing...not skin or architecture. 

    I am not sure anymore if your issue is the same like mine. Difficult to judge by the posted image.

    Anyway, if you have Affinity Photo you can check the image there (I don't have Photoshop so can't say something about that one).

    Attached are two picked colors shown in 32 bit color mode. Both colors seem to be white but one white is above 15000 units the other a few pixels away is around 2. This contrast seems to be to much for iray smiley.

    What I did for the second render:

    - painted over the sun with a pixel layer using the values shown in the fourth screenshot

    - reduced the blue saturation

    - exported as hdr and loaded into environment

    - increased subd of the clothing to 2

    Render is now better. But the hard sun look is gone (and still to blue). I would now fiddle more with the hdr in Affinity and / or add a sun light or mesh emitter in Studio. But not sure if this would work in your case (and if you have a PS version that can handle 32 bit images). Sorry that I can't be of better help.

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  • dawnbladedawnblade Posts: 1,723
    edited March 2021

    Check if this HDRI changes the "Shadow Intensity" "Ground Texture Scale" in render settings. I've noticed that with this pack, and particularly when you apply some of the Dome Options. It adjusts the shadow intensity "Ground Texture Scale" higher/lower for distance/closeness.

    Post edited by dawnblade on
  • dawnbladedawnblade Posts: 1,723

    Correction: It's "Ground Texture Scale" and it changes when you apply some of the Dome Options in this product.

  • cajhincajhin Posts: 154

    @Anim: ah, the Chinese Garden hdr :)

    That one was the first time I stopped and said What? Something's wrong here. That light is *harsh*. Gives some interesting shadows on the face, but large areas of skin look toon shaded.

    I was hacking on the hdr, just to see how this works, results attached. I turned the sun core down (just 10px diameter) and the whole sun up to compensate, color balance towards yellow/red.

    If I had to do it again, I'd try to copy&paste a sun from an hdr I like... there's probably a professional approach, but I couldn't find it.

     

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  • SotoSoto Posts: 1,440

    I am having this issue and disabling the bump helps, but... I need the bump.

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  • AnimAnim Posts: 241
    edited March 2021

    @Hellboy

    maybe increasing the mesh resolution can help (hopefully you have not already maxed it out). By the way, the issue is still there in the render without bump but less obvious - check the edge artifact on the lower arm.

     

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  • MelissaGTMelissaGT Posts: 2,611
    edited March 2021

    Hi ya'll...I can finally post my final piece now that the promo has been released for the character:

    Unfortunately, I could not come around to an actual solution. I didn't have issues with shadows on the character herself, just the clothing, and that was all at subd 2, so I don't think the problem was the geometry. In the end, I ended up rendering the piece two times...once with spectral rendering turned on, and again without, just to get the right skin. So in the end, I still have no idea why this specific HDRI is a problem. It's super high contrast as you can see, but all the HDRI's in the pack are just as high of contrast and don't have this problem so I'm at a loss. 

    Post edited by MelissaGT on
  • SevrinSevrin Posts: 6,306

    melissastjames said:

    Hi ya'll...I can finally post my final piece now that the promo has been released for the character:

     

    Just curious?  Why wouldn't these promo images be released earlier?  Seems to me that promos like this, as sales support, would be at their most useful as soon as possible after the character is released.  Klementine was released two weeks ago.  I mean, better late than never, but if you wanna maximize impact, sooner = better.

    Nice image, by the way.  She looks kind of depressed in the store promos. 

  • MelissaGTMelissaGT Posts: 2,611

    Sevrin said:

    melissastjames said:

    Hi ya'll...I can finally post my final piece now that the promo has been released for the character:

     

    Just curious?  Why wouldn't these promo images be released earlier?  Seems to me that promos like this, as sales support, would be at their most useful as soon as possible after the character is released.  Klementine was released two weeks ago.  I mean, better late than never, but if you wanna maximize impact, sooner = better.

    Nice image, by the way.  She looks kind of depressed in the store promos. 

    No idea...I don't run the group, I just do pretty pictures, lol.  

  • My apologies for bumping such an old thread, but I was having this same problem with one scene of mine (the HDRI used was one from DimensionTheory's beautiful Skies of Gaia 2 set).  No amount of subdivison, removing normal maps, or messing with smoothing helped anything.

    I accidentally figured out the problem with mine.  Toggling the Dome Mode from Finite Sphere to Infinite Sphere smoothed all the chunky and artifacted shadows I was experiencing on my clothing items.  I hope this helps out someone going forward!

  • barbultbarbult Posts: 24,243

    Lucky Stallion said:

    My apologies for bumping such an old thread, but I was having this same problem with one scene of mine (the HDRI used was one from DimensionTheory's beautiful Skies of Gaia 2 set).  No amount of subdivison, removing normal maps, or messing with smoothing helped anything.

    I accidentally figured out the problem with mine.  Toggling the Dome Mode from Finite Sphere to Infinite Sphere smoothed all the chunky and artifacted shadows I was experiencing on my clothing items.  I hope this helps out someone going forward!

    That's interesting. I'll check for that next time I see that kind of problem.

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