A Guide to Skin Colors for CG Artists
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- čas přidán 16. 07. 2024
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This video is a guide to understand the important elements that contribute to skin coloration and it is aimed primarily at 3d character artists but can be useful for anyone who wants to develop a deeper understanding of the topic.
References:
n3m0.org/
reality.cs.ucl.ac.uk/projects/...
reality.cs.ucl.ac.uk/projects/...
citeseerx.ist.psu.edu/viewdoc/...
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Thanks for watching!
00:00 Introduction
01:03 Skin Coloration Research
09:39 Practical Examples
19:27 Absorption
Priceless explanation. Thank you a lot for your videos😺
You are amazing, thank you!
Hi, Laura!
Thank you so much for this video and these links. I am so far down the rabbit hole of trying to figure out a system of basic skin colors to use as a jump-off for starting skin textures for characters, and I feel like I may never make it out. This video feels like a bit of solid ground to stand on and I'm very grateful.
I've been looking at the Monk Skin Tone Scale (a 10-point scale if you aren't familiar) as a jumping off point. The lightest tones (1, 2, sometimes 3) often look lifeless to me, but once I redden up some patches and paint in some freckles they start to look a bit less like marble or something... I'm probably over-determined in this, to my own detriment, but I like that the Monk scale starts off with concrete values. I can start with a hex# to get somewhere I believe in. Looking at the Monk skin tones and then at “real people” (on TV or whatever) those colors often seem good in hue but off in value. Looking at your color gradient look-up chart with the melanins spread it does inform the way I might approach adjusting the Monk scale - using these hues to jump off and adjusting them down in value to suit the individual character. So, for each of those colors I'm trying to come up with some set SSS colors that suit them. One of the other online spaces I see talking about something similar is the make up industry, and how they seem to discuss skin undertones (with a general cool/neutral/warm division). This seems to relate to our discussion of hemoglobin/dermis coloring in SSS. I don't know anything about make up, and not too much yet about skin texturing and shaders, but you seem to know about both. Would you say that it's a one-to-one correlation between “skin undertone” and dermis/hemoglobin color? And how much is the dermis/hemoglobin color changing in light vs dark skin? We all have similar blood under the surface, do the SSS colors start relatively similar to each other across the skin value spectrum, or does it move up and down more and follow the epidermis/surface color? And do you think “towards cool/towards warm” would be the same (say as an RGB +/-?) across the spectrum of skin colors?
I read both the Donner & Jensen 2005 and the SIGGRAPH Asia 2008 papers. Interesting and informative. The math might as well be redacted as far as I can follow, but the basic concepts I can generally make out. So on the second paper, which talks about this inter-layer that absorbs pass-through light between the epidermis and the dermis, which they use to introduce veins that create dark regions... how would you implement something like this in a system that was just two layers - an albedo/diffuse/surface texture and then an SSS color or texture image? In the stream about character creation from which you posted the skin segment (again, thanks!) they use a mask-type image to drive how much SSS there is. That seems like a good way to drive this idea, but... how? Let's say I'm running my subsurface generally at 0.015 (I don't know if BSDFs are consistent in their parameters across programs, or if they are not relatable to each other in that way. I happen to be working this out in Blender). If I wanted to still use that value as a base but drive it with an image, would I start with a field that was HSV Value 0.015? (Or possibly the opposite, 0.985?) And then paint up or down from there to increase/decrease SSS? And that wouldn't affect the SSS radius values, would it? And for thin areas, like eyelids, which end up blue from short blue radius values, could this be used to mitigate that effect? Or is masking in a separate shader that has slightly different SSS radius values a better solution for thin areas like eyelids?
Sorry for this ramble. It's an indication of how in the fog I am. But also, it's a reflection of how much you've given me to think about. A lot of avenues to investigate. Thanks again for your videos.
Oh yeah render lady is back...😎
You picked a very basic topic. as an artist I always struggle with skin tone. You are amazing. 👍
Very interesting. For me especially the part about using the same red color for different part of face was useful. Personally, depending on what type of character I work on (skin color wise), I prefer painting the base skin in zbrush using polypaint, since I think it gives me more freedom. And add as much details to it as possible. Usually the result zbrush polypaint gives is a bit different than the one we see in real-time ( I think it's mostly because of the zbrush skin materials which are not that accurate), so after baking the polypaint to texture, I take it to painter, add more details to it, & after I'm happy with the result, send the finished texture to photoshop & compare it to a texturing xyz maps to see if it needs to be darker, lighter or needs color adjustments ( again base on the skin color that the character has) . I'd like to know your opinion on this method. Anything you think is helpful to add to that workflow to add quality/reduce time? BTW, great video as always.
Honestly I think your approach is solid. There's clear experience behind your words so as long as the end result is artistically on point I think it's all gravy. You calibrate your values and hues in the end in Photoshop so you end up where you need to be. I've painted a few albedos myself in Zbrush and really like it. I think the drawbacks to creating albedos in Zbrush are 1- That it's harder to adjust the intensity of certain details if the ''mix'' isn't quite to your taste since Polypainting on layers doesn't always work properly and 2- There's more steps involved in extracting a new iteration on the albedo if, once in the target engine, the details somehow need adjustment. I think creating albedos in Painter is more beginner-friendly for these reasons, it's very flexible, but I would never question an experienced artist's work methods if the end result is artistically on point. Have you tried making an albedo in Painter? What did you think of it?
@@Outgang Thanks. I'm glad to know you approve this method. I agree with the drawbacks that zbrush have in case we need to adjust the details. I forgot to mention that when polypaiting in zbrush I try not adding things like moles, freckles and such. It's more of a detailed, yet generic way of painting skin color since I like to add those small details in a non-destructive way in Painter. Especially since I can add some height information to them as well ( which again, I prefer not doing so in zbrush ). One thing I did was to create a few planes, subdivided them, and made some color palette for each type of skin ( Asian, caucasian, african-american, native-american & etc) by adding different colors that we find on each of those races' skins to those palettes. It make this workflow incredibely fast since I don't have to do it each time. It took a bit of time studying different skin colors but damn it was worth it.
Yeah, I've painted skin entirely in substance painter before. It's more forgiving when making a mistake since we use masks & we are also able to change the color on the fly for each part ( different reds, blues, greens & etc, different opacity for each which is hard to achieve in zbrush sometimes).
thanks fot sharing!