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Modron
22-Aug-03, 22:32
I have seen alot of really great examples of skin textures here. Can someone give me advice on how to reproduce this effect?

zaz
25-Aug-03, 05:22
Ok, I'l bite, but I make absolutely no claim to being an expert, :D.

I've been fighting this battle myself, spending literally hours rendering and re-rendering trying to get a skin texture right.

The first thing to remember is that there is no one right way. The second thing, and I might be wrong on this, but I believe blender imposes some limits on how good of an outcome you can expect ... in my opinion at least. Some of the work you've seen that impressed you may have been rendered in yafray or another renderer external to blender.

In another article, someone pointed to the Blender Materials Database -> http://www.geocities.com/pollythesheep/matlib_index.html

They have a skin texture there that bears a striking resemblance in structure to what I stumbled on independently. The particular texture there though is way too red/pink for my tastes on my systems.

The similarity between the skin texture there and mine is that it has 3 primary color components, 4 when you count the specularity, and we have very nearly the same saturation of our colors as well as similar hues of colors. I made the base color of my material pretty close to theirs with about the same saturation, around 0.3. This base tended towards a yellowish pink "grey" (read low saturation as in the 0.3 S value), sort of an orange, but not quite. I then layered on this my first texture which was a cloud procedural texture, as did they, that only contributes color which was a slightly more saturated red. I also tweaked the Col slider in the lower right to take this texture channel down to the point where it was barely noticeable when rendered, about 0.5 with my choice of colors and lighting.

Adding a bumpmap of some sort to rough it up a bit and let the specularity contribute a bit more is also needed. In their case, they used the stucco procedural texture for a bump map, in mine I had an image with skin pores on it I got from somewhere.

I also added another texture to mine to add some more imperfections which I tended towards a bownish grey, sort of like freckles, age spots, whatever. These were very sparse and I used the dots2 procedural plugin, available at http://www.five-o-clock.de/blender_plugins/dots2.html and other places.

As far as specularity, I tended towards a pinkish grey at 0.250 spec. Theirs was more orangish grey with only 0.05 spec. I think in many cases my spec is too high, but I've also had a problem in the skin being too dark overall so everytime I lower the specularity I end up raising it again later to add a bit more brightness to the skin. Need to tweak my lighting more I think, then get my spec down. A lower spec would probably let me go even lower in some of my saturations, which I believe would let me get at least my base color closer to the images I've used for reference.

One thing to realize, if you haven't already, is that skin, like many other textures, isn't just one color. You have to layer in the colors, striking a balance between the various components to eventually get something that has some realism to it. Under the right lighting conditions, I really like my skin. However it tends to be very sensitive to lighting conditions. I'm not sure if this is because I'm a bonehead or because of limitations to blender's renderer and/or lighting model.

Also, a person's skin looks very different under different lighting circumstances. I'm not convinced yet that blender's internal renderer will allow you to make one material that will work under all lighting conditions. Skin also varies in color from one location to another on the body. I found a book called Digital Character Design and Painting, ISBN1-58450-232-0. While its geared towards painting images digitally, I've found a few useful tips and references in there for my blender work.

As far as skin tones go, there are really only two pages, more like a page and a half, on it. But it does outline something I'm trying to get right in blender. The basics from the book are that a persons general skin tone/complexion is found in the center of their chest. Moving out from there, the skin gets ruddier and darker and the hands, feet, elbows and knees have much more red to them. There are a few more tips in there, but if you aren't going to paint digitally, it may not be worth purchasing. I got mine at my local Borders, it wasn't hard to find.

Finally, after years and years of dealing with RGB, I became a convert to HSV in my endeavor here. It was just easier for me to make the changes to the colors I used. If you haven't played with your material colors in HSV yet, you may want to try that. HSV helped me find my colors a lot more than I expected and was especially useful for me when it came to working with the "colors" of grey I needed. Pick a color via Hue and lower the saturation to make it grey. I haven't spurned RGB yet, but I do use HSV an awful lot now.

I hope this helps you out or at least bumps your post to the top again so someone who has more expertise than I in this area can give you the right answer, :D.

Zenitor
25-Aug-03, 05:45
http://www.cgtalk.com/forumdisplay.php?s=&forumid=46
you could spend a couple of days looking here ->
http://www.cgtalk.com/showthread.php?s=&threadid=63930

Door3
26-Aug-03, 13:21
I believe blender imposes some limits on how good of an outcome you can expect ...

It ain't the tap shoes kiddo, it's the dancer!

MrNightmare
26-Aug-03, 14:17
For a start, you can search google for free poser textures...there are some realistic skin maps for that (ahem) program.

Modron
26-Aug-03, 18:11
Thanks guys! Very helpful! You were right about the HSV. Seems to be working nicely.

Setanta
26-Aug-03, 19:39
For a bit about creating realistic skin textures, you might want to try


http://www.3dtotal.com/team/Tutorials/benmathis/benmathis_textures_1.asp


It's part of a tutorial and goes into uv mapping a skin texture in some detail.

Setanta

zaz
27-Aug-03, 12:53
I believe blender imposes some limits on how good of an outcome you can expect ...

It ain't the tap shoes kiddo, it's the dancer!

Yeah, my blender dance needs a bunch of work ... anyone got an extra right foot to trade for one of my left feet ? :D.

I wouldn't have mentioned blender limitations though if I hadn't seen posts about it by people much more experienced than me or if I'd seen output that I knew came from blender's internal renderer that had a real impressive skin in it. I've seen some good examples here, but I've noticed a lot of people use yafray to render and unless the example states it was done entirely in blender, I can't assume that.

Door3
27-Aug-03, 15:26
I don't think that there is anyone here who does not wish that they were a better blenderizer.

I find tho that no matter what method you use, you have to learn to work within it's constraints. If you have a seat of Renderman and a ten acre Linux render farm, you still have to set it up explicitly.

As for Blenders scan line renderer. It has gracefully rendered everything that I have ever thrown at it from hyper-photorealistic to cartoon. Worked consistantly and included Nurbs surfaces, IPOs , UV mapping and other non-extensible information that I would have made a carreer of trying to export with interpeted coding languages like Python.

It also makes alpha channel transparencies that work with every other software that I composit in.

Personally I like it and I honor Ton for making it.
:D

zaz
27-Aug-03, 23:34
Just for the record, I wasn't complaining about the renderer. I don't think you were "accusing" me of that, but I just don't want people to misunderstand my statements.

And I agree, everything has its own limitations and/or price. The scan line renderer in blender does a very good job at a much lower cost in time than many other solutions. Its all I use now and while I've played a bit with exporting to pov and yafray, I'm not convinced its worth my time and effort right now to use those.

Door3
02-Sep-03, 13:52
I don't think you were "accusing" me of that, but
No way, man.

Heres the thing tho, if you follow these discussions (and obviously you do) then you know that the general attitude is that the renderer in Blender is about as sophisticated as a crank on the front of an automobile. The shrugging rationalizations of "Well it's free" or "If it's all you have..." are not just weak, they are stupid.

It's that old sad story of users not realizing what they have because they got it for free.

If you want good skin tones & you know how to use the medium, no problem.

If you want good skintone from some shortcut software and do not know what you are doing, it may not work out.

But enough with all of that!

We are talking about how to make skin, right?
Maybe we can work it out here and Modron would write a tutorial on the subject.

http://www.door3.org/skin.png

Skin is not a mesh.

The underlying anatomy is what you are actually percieving even as an image, because of your other experiences with the stuff. I had this girlfriend once who...well maybe that's a story for another time.

This bit of skin that you are trying to image. Hopefully without taking the tone of a television repairman who asks you "is it plugged in?"
Did you layout the oily spots, the skrunched spots (grab something toght and look at the colortone of your knuckles) , did you figure anatomical wrinkles, did you UV map the freckles, liverspots, littlehairs, abraisions and like that, that tell the story, did you create enough conrtast for effective imaging with the clothes and background.

That may be a start.

Modron
02-Sep-03, 20:32
So far the best result I have gotten was achieved with:

UV mapping

Multiple texture channels

A touch of vertex paint

A dash of radiosity

Star*Gazer
03-Sep-03, 00:23
Vertex painting is great, thats what I'm using right now for one of my characters.
http://us.f1f.yahoofs.com/users/97f74f20/bc/My+Art/JimmyMonsternoeyes?bf3EXV_APSqn0tT_
And if that doesnt show up then heres the link to my yahoo briefcase...
My Briefcase (http://www.briefcase.yahoo.com/jimmythelonegunman/)
That should work if all else fails. Ihave the hardest time posting pics on this forum. Anyways, yeah vertex painting and the stuci texture in Blender work pretty well and you should look at your own skin to get an idea of where all the colors go, as far as textures for hair and things like that, UV mapping as many will say :).
Jimmy