Moire patterns in SSS! How the heck do I prevent them?
warrenao
Posts: 61
I'm really, really starting to hate SSS.
I've seen discussions about patterns in skin textures created by it, but I don't think I've really seen a discussion of how to consistently keep them from happening.
The attached is an example of what I mean. I'm using DS 4.9, rendering to 3DL, and if I have a figure with SSS, it's just about 100% certain that its skin will render — at anything like "distance" from the camera — with moire patterns. Close up, this doesn't seem to be a serious problem, but if the view is far enough away for the whole body to be visible, the patterns appear every time. It seems to be made worse when I use any sort of lighting, as opposed to rendering an unlighted default. (And, of course, in low-light conditions, I get that weird atomic glow.)
I have tried disabling SSS in the figure's surfaces. I end up, with disheartinging frequency, with something that looks like it's performing in blackface.
I've tried looking or SSS-off options in the materials, and if those options are available, sometimes they actually do seem to provide an SSS-free surface. However, frequently, they don't appear to change anything.
I don't think I'm getting into a conflict with surface ID numbers, but if that's the problem, and in order to solve this I'll forever have to manually go through every figure I drop into a scene, looking for ID conflicts, then SSS will quickly become far more trouble than it's worth.
This is really getting infuriating. It's kind of stupid to create something that allegedly produces more realistic renders, but in fact results in figures that look like they've got terminal eczema, or the worst case of wafflebutt ever, or radioactive figures in shadows, while at the same time dramatically and pointlessly increasing render times.
So is there a consistent, straightforward way to eliminate the moire patterns in SSS or, better still, disable SSS completely, on demand, without it adversely changing the coloring of the figure's skin in the process? I can't tell you how many scenes it's ruined for me, and I'm getting pretty bloody sick of it.
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Comments
This will explain what is going on with the shader http://docs.daz3d.com/lib/exe/fetch.php/public/read_me/index/16324/16324_subsurface-shader-base.pdf . You can get rid of the effect with some adjustment based on distance/size of the figure in the scene. Removing sss will always change how the skin looks because it is part of how the skin color is created.
Funny story. I have that document but don't recally seeing the single image associated with the Shading Rate section. I'll play around with it and see what shakes out. Thanks!
No joy. I've taken the shading rate as far down as 0.1, and nudged the shading scale up to 1.0, and it's made no perceivable difference.
I really, really need these patterns to go away.
Not just shading rate, but shading scale, too...and you also need to make sure that if there is more than one figure in the scene, that they each have a unique SSS ID, especially if they are using the same skin.
I did push up the shading scale, to 1.0. I'll try increasing it further. No one is using the same skin, though. I'll double check the ID's, but right now, SSS is proving to be far more trouble than it has ever been, or ever will be, worth.
Alas. Shading rate 0.0010, shading scale 10.0, independent ID's verified. It seems that the shadng scale is too high here, since the skin became considerably worse at 10 than it was at lower values.
I've run into this so many times... the 'lizard-skin'. What I always do, and it has worked every time, is do a surface selection of the character that says (something like... I'm not at my home computer right now) select all SSS for this character, then change the SSS ID number (what mjc1016 is referring to) to something else. It probably has a ??? for the ID number, but one of the surfaces is conflicting with another character. I usually will throw mine up into the 200-600 range. It's always worked for me, and I get it all the time since one of my main figures seems to conflict with pretty much everyone else... haha I never had to change any other setting for SSS to fix that.
You may need to change multiple figures like this in a scene. I had a scene with about 20 figures and had to change 6 of them as I couldn't figure out which one was the trigger.
Often there will be more than one SSS ID number on a figure....and it could be something like the eyes (sclera) of one figure having the same as the skin of this figure.
What I had not done was use the actual surface-selection tool to select 'all AoA surfaces used by figure BillyJoeBob', etc. The ID field did indeed come up with <?>, so I set it to a single value for each figure (100, 200, etc.). It's rendering now; we'll see.
Well. After successfully fixing the skin in other figures, I'm still running into trouble with this guy. I've tried multiple settings for both shading rate and shading scale (everything from 0.001 to 1.0 for the former, and 0.3 up to 10.0 for the latter), and still he gets these moires. The other figures are no longer showing this problem. It's precisely this level of trial-and-error BS that, in the second decade of the twenty-first century, is particularly galling.
I hate SSS.
Are there any other practical options avaialbe to put an end to this nonsense?
Try a shading rate of 1 and a scale of between 0.1 and 0.25.
Giving that a shot now, starting at 0.1. Thanks.
Still no luck. I incremented the scale from 0.1 to 0.15 to 0.2 to 0.25. All four renders came out like the attached. There is quite literally no difference between them. :\
Take a look at the Bump Noise Strength value. I had a character that looked like yours and none of the suggested fixes worked. Turned out that the Bump Noise Strength parameter was set to something like 45%. When I turned it down to about 12%, the lizard skin went away.
Hmm, bump noise strength is at its default of 0.0%. Bump strength, on the other hand, was at 25%, which was not the default. I reset that, and am doing yet another test render.
That made no difference either.
I guess I'll have to get a merchant resource kit and start making my own skins, without SSS, and offering them for sale, because this is ridiculous.
You need to slow down and do this systematically. In the Surface pane select each surface that you feel belongs to the same Group ID, assign them a unique number and make sure the Shading Rate and Shading Scale values are the same (no "?" ), I like 4 and .5 respectively.
I have done that. The correct surfaces have the correct, and unique, ID's. The shading rate and scale values are the same.
At the size shown (figure around 300 pixels high) i would simply turn off the subsurface scattering. The SSS on skin is visible in the range of very few millimeters, which is far below the size of one pixel in your render. Which in turn would require a very small renderer shading rate. E.g. if the size of the human is 2000mm, your render is 400pixels you would need a shading rate of 400/2000 squared = 0.04 to have at least one sample per millimeter. Which is rather slow, for an effect that will not be noticable anyway.
However, If you want to keep the sss, the sss-scale should be 0.1 (if the values are based on the most typical measurements), and i guess an sss-shading rate of 0.1 should do it (that is the shading rate in the surface settings, not in the render settings). Since the shading depends on the image size: alternatively you can also render a bigger image instead of lowering the shading rate - the effect is mostly the same (except for the speed).
Unless you want to render a 6foot gummibear or something like that. Only then i would raise the shading scale higher than the 0.1. (A lot of premade settings already have a higher value, to emphasize the sss-effect and make the skin look more plastic, but that is in the field of "artistic freedom" where basically no rules exist).
Hmm, I'm not seeing a setting anywhere called 'subsurface scattering'. There is a simple toggle for 'subsurface off/on', but as I recall that's the setting that turns the character's body dark. Is that the setting you're referring to?
Okay. Disabling subsurface entirely does eliminate the patterns, but it still leaves me with a somewhat darker looking character. However, it also seems to reduce render times. (The character's skin was set to 75% SSS as well, which I think is gratuitous.)
I think I can live with a somewhat darker character. If that's the only alternative to random moires, it'll do for now, but I still think it's past time for someone to produce a set of decent skins for G2 and G3 that do not use SSS at all.
ok just so we are clear not all sub surface scattering does that. For example it does not happen in Iray with SSS. And your just not going to get anywhere near realistic skin with out SSS. If you look around though there will be skin sets from that era that do have alternate settings that are not based on the AoA subsurface shader base.
It may not happen in Iray, but I did menton I'm using 3DL. As for realistic rendering … a model at 300 pixels tall without SSS looks considerably more realistic than a model at 300 pixels tall that's got moire patterns all over its skin. SSS might well be of great value in close-ups or very high reslution renders, but at anything like an intermediate or long range, it is worse than useless.
Disabling the SSS usually requires to set the diffuse color to 100%. The reason is the way the Subsurface scattering is used in practice by the shader creators; in an ideal world you would use either subsurface scattering or the diffuse color, never both at the same time. But character creators also want to use stock photographs to create textures from it. These textures can easily be plugged into the diffuse color, but not in the SSS-color (at least not without loosing a lot of detail). As a compromise, shader settings often contain 50% SSS and 50% diffuse color (or some other ratio depending on this and that). So when disabling the SSS usually the diffuse color has to be raised to 100%. Sometimes it is in the "Diffuse strength" that needs to be set to 100%, sometimes it is the "Diffuse color" that needs to be set to white instead of grey. Often it is much easier to simply use an easier shader (like the DS Default Material) and simply load the textures, though, instead of wading through all those options and adjusting values, especially when there are other settings than SSS that get into the way.
I understand your using 3dl. I used it for 9 years and worked with the AoA extensively. Nor was I the only one by any stretch of the imagination. And it is the only one of the sss enhanced shaders that has that issue. None of the characters that have omUberSurface shader settings are going to have that issue even if they are using sss. There are a pretty wide variety of characters that have both AoA and uberSurface settings as well so there is an option to have sss and not have any risk of that issue showing up.
Thanks, millighost; that makes a good deal of sense. The diffuse strength for my problematic little Captain Speedo was set to 50% (the color straight white). I nudged that up to 100, but he came out just a bit too … vibrant. He's much more plausible at 70%. And with SSS off entirely on everyone, the render time is really quite dramatically reduced.
I'm really not expecting brilliance or ideal images rendered from something grabbed and placed out of the can, with zero adjustment; I know that's not realistic. I am, however, expecting that any generic thing I drop in a scene will, without additional tweaking, render mostly within the bounds of realism. The problem I have with SSS is that it adds a set of complexities that require far more work to resolve than any benefit they add; what should have been a five minute render has turned into a couple days' worth of what the heck is going on here.
It would be nice for models to be created that allow for a quick toggle of resolution so they could be easily switched between modes when rendering for closeup versus distant. It would be even better for Daz to do that automatically based on view distance and camera focal length.
I'll keep that in mind going forward; thanks for the pointer. It's unfortunate, because in some situations, particularly rendering translucent surfaces, I've liked being able to nudge the AoA subsurface settings. But they really seem to be toxic at distance.
Not sure this is the help you're looking for, but the only reliable fix I've found for that issue (I got this all the time too, in 3Delight...) was to use the Amazing skins shaders on all my characters. As far as I remember, it never happened to me with V3Digitime's shaders.
Link to the shaders : http://www.daz3d.com/amazing-skins-for-genesis-2-female-s
Interesting. I'll look into that!
I was also messing around with the skin builder for G/G2 (http://www.daz3d.com/skin-builder-for-genesis-and-genesis2-female-s), and noticed it doesn't have a load of SSS freight either. Unfortunately there doesn't seem to be a male version for that, nor a G3 version, and it gets … funky with genitalia, both male and female. However, it's handy for making quick and dirty tan lines in addiiton to custom skins.
You seem to have this impression that SSS is bad.. It is only bad when it is used improperly.