4.15 rendering out skin much brighter than 4.14 (edited title)
naughtyroad
Posts: 40
Edit 2021-2-16: leaving the text below for historic reasons, but my conclusion so far is that something major changed with SSS in the iRay version used in 4.15 (I'd consider it a bug), strongly affecting character skin and hair, and I have fallen back to 4.14 to be able to continue production as render output of 4.15 (up to and including 4.15.0.9) is currently unusable for me.
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I've noticed that recently, my renders seem to come out a lot brighter than they used to. Point in case, see attachmed image.
Both were rendered from the exact same scene (no changes in settings applied) Appart from the 'headlice' issue (discussed here), the newer one is clearly gotten much brighter.
Obviously, the workaround is to drop exposure (about a full point seems to do it in this case), but I was really expecting the results of renders to be somewhat repeatable over time. I tend to render out sprites in series, and might add sprites to a series over time to add new emotes to a scene, and having to eye-ball the exposure on scenes to get them to match my existing stuff is no ideal.
Full disclosure: my hardware's changed a bit over time, the old one was rendered on a 1060 6GB+2070super setup, now I have a dual 2070 super setup, but since it's still being rendered in the GPU then and now (and not on CPU as I'd expect that might render out differently), my expectation would still be a reproducable render though.
Is there something that can explain this behavior, and something I could do to get it to render out exactly the same as it did a little over a year ago?
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Good character btw, I'm mexican and she have some etnics from here.
Now to the point:
Looks like a simple Exposure value tuned on 12 (default value must be 13), just increment the actual Exposure Value related to your actual value on your newest render, I've included some images that can explain that I want to say.
Default Value: 13
Low Value: 12 (probably your issue is because of this)
High Value: 14 (the setting that you should set to back to normal)
Could be two different versions of Studio. One done in 4.12 and the other in 4.15?
Cheers, I get a lot of questions and speculation from my users about the background of that character and the other lead lady in the game. I shant spam this conversation with links though, it's available for free out there.
Sadly it's not a problem with exposure flipping from default. I'd already set the exposure on that scene when I originally saved it (by modifying the film ISO) so that was saved with the image.
I'm wondering now if it's the exposure per se, because looking at the clothes, they seem to be pretty similarly lit, so I'm wondering if it could be a skin issue (skin's Elizabeth for Victoria 8 with some teaks to the color and translucency to change the skintone). I'm wondering if that's started to react differently to lighting recently.
Attached an image lit up with the same (homebaked) HDRI and (nearly) identical lighting setup, and you can see it even more clearly there.
The character skin's Rebekah for vic 8 with similar tweaks. There's almost no discernable seam in the sweater between the old and new render where they join up, but with the skintone it's a very striking difference.
Yes, definitely, I've upgraded with each daz version. I'd hate to have to start keeping different versions around manually though (which is a real pain) just so I can render some additional emotes to an existing range (or redo the entire series after redoing the lighting).
If it's the case that the same scene starts to render out dramatically differently over different versions, that'd be a real bummer.
iRay version also changes with new versions of DS too.
DS 4.12 iRay ver RTX 2019.1.1 (317500.2554)
DS 4.14 iRay ver 2020.1.1 (334300.4226)
DS 4.15 iRay ver 2020.1.3 (334300.6349)
Hmmm, this is getting a real problem for me, it's getting so I can't add any new images to existing series. Another example, this with the latest public build that's just dropped. It's like someone's turned on the light in there, but only the character hair and skins are affected, the bed prop's exactly the same in each. There's no way I can use this in the existing series, I'm gonna have to redo a good 100 renders and a fudgeton of post work again so they all match up again and that could be one or two weeks of work. It's an absolute nightmare.
I'm stopping production on my current project and taking to support to request an old version untill this and the other issues in 4.15 are fixed (the weird overly bright hair and headlice specling issues I mentioned earlier are somewhat mitigated in the latest beta but not completely solved - at least for the speckling, I just tried - and I'm not at all convinced that issue and this one aren't related).
Damn, hope the old version comes through soon.
Sincerely I don't see any remarkable difference in both renders at such point to make stop on your project, maybe you are overseeing this.
as I can see your project makes use of nudity, I'll be more worried about your areola textures than the hair brightness, and about nudes I'm very expert in such area.
just my expert opinion (No I'm not humble)
I wish I was, friend.
/
You'll see it when you put them over each other and flip them, the difference is very dramatic then (as you could tell by the earlier image where I spliced the image of the girl in two).
As I'm showing variations of these images one after the other while they have conversations and interactions in the game, it's like someone shines a flashlight on them and then turns it off again, when going from one of the old images in this series to a new one and back again. So the new renders are completely unusable in this existing series.
Handling it post is also not an option, because the bed and clothes are completely unaffected and render out exactly the same, so if I tweaked brightness or exposure there, all of a sudden the bed or the chothes turn several shades too dark for one frame.
It actually looks like the light is brighter rather than more gloss. Just a thought you haven't got Dual Lobe Specular Weight on in one and not the other have you?
Interesting point, and no, tbh I'm not entirely sure what it does so I've never fiddled with it.
Attached the settings for dual lobe for the leftmost character, the settings probably came in with the Elizabeth skin she's using (i've tweaked a bit in the colors and opacity when I created her but never touched the other stuff, and I've used that character preset in all my scenes ever after). There are some setting at default in there; I wonder if the defaults might have changed with the newer version? (if it wasn't explicitly set in the scene, it'd use the new default upon loading, I'm guessing. I'm not sure if that makes sense or not)
Without access to a 4.14 or earlier, I can't tell, but I'm gonna play with those settings a bit, see if that'll help me get close enough to what the original looked like to be unnoticable.
Well, experimenting with dual lobe did turn up something interesting. In trying different values and matching them against the original, I found spotrenders now render out much darker than the full image (had me fooled I was really onto something until I noticed it was only in spotrendering).
I know spotrenders can differer quite a bit from the full render and occasionally need some brushing to blend in nicely over the full one, but I've not seen it quite so dramatic before.
Actually, if the area is small enough (say about 15% of the image), what the spotrender turns out is pretty close to how the old daz versions use to render out, which is exactly what I want. The larger the area, the more the character skins brighten to the point where it's exactly like a full render again if you spotrender almost the entire image.
I wish I could show the full image because it's much more noticable on the rest of the body, there's a bit of an example, with the spotrender on the slightly lower left half, looking like how it rendered out in previous versions.
It might be worth trying the latest Daz Studio Beta version 4.15.0.9. The Iray version Iray 2020.1.4, build 334300.6885 in DS 4.15.0.9 has this comment:
Cheers, I snagged 4.15.0.9 as soon as I saw it and sadly the issue is still present.
First of all I'd also like to share some compliments for the render, that girl looks very nice IMO. Plain out cute.
Second... I think Zilver raised a very good point here: could this be an effect of the render engine? Because as I stated in another thread: I don't have this issue myself, but now I'm realizing that my renders are mostly based on 3Delight instead of iRay. Making me wonder what would happen if you were to try another render engine? 3Delight is probably out of the question because you'd lose some of the photorealism which iRay achieves but there are also 3rd party engines available. Such as Octane for example, maybe that could provide a solution here?
My reasoning is that this way your render engine would remain the same no matter how many DS upgrades you get. I only base this on my experiences with Luxus & Reality. Though LuxRender got whacked and "rebuild" into LuxCoreRender (effectively rendering all DS plugins useless, great going there) I retained access to the original engine through Reality (and my backups) so I still get to enjoy all the stuff you can do with it. Despite DS upgrades and a whacked open source project.
Maybe food for thought?
Some interesting points, to be sure, but right now I'm in a right pickle as I have to make a choice between redoing about 90 renders in a series plus all the post work (and might do all that for nothing if a fix drops in week or two) or call a production standstill until this is resolved (if it ever is). Neither is very attractive. On hindsight, I should have kept copies around of previous daz versions, but, well, hindsight.
Right, after ehem, procuring a 4.14 (which was not a fun experience I can tell you) I can confirm that this issue does not occur 4.14.0.10 pro 64. So at least I'm back in production, that's something.
Some follow up for anyone interested: I got a hold of a friend running an 3090, an running latest official 4.15 release to see if we could reproduce the issue. I'm running twin 2070supers. We could confirm that he's seeing the same brighter skin issues I am.
The character used has the Default Genesis 8 skin. The pose is slightly off from his (3090) renders for some reason (used content gatherer to transfer but seems it didn't pick all, but that's not important).
In the first set of images, we used the scene's default lighting (homecooked HDRI + regular spotlights). If you open all and flip between them, you can clearly see the skin is a lot brighter with any 4.15. Also quite clear, the robe doesn't get affected between versions. SSS issue indeed, or translucency? We then did a run with "sun/sky only" for lighting, and found the same result. The issue doesn't seem related to HDRI or regular spotlights.
I'm thinking that since the 4.15 images don't look bad per se unless you look close, and a lot of artists probably do unique images, this issue's gone mostly unnoticed, but my guess is it's happening for a lot more people, if not all.