I got into this whole 3D game to make cool fantasy and sci-fi art. To that end I started using Daz 3D to build characters for my scenes, but I could never quite get the renders to look the way I wanted using the default 3Delight renderer provided with Daz.
So with this in mind, I began playing around with exporting the Daz scenes to into Blender and using the Cycles engine to render them. Still, nailing “realistic” skin was an issue.
I looked at a zillion Cycles node setups, but none seemed to give me the results I wanted. I soon realized that every project would be different, and there would be variations from model to model, and texture to texture. Simply pasting in someone else’s node tree wasn’t going to give me the results I wanted.
I watched and read about 100 “realistic skin” tutorials. Finally, I realized what I wanted was not necessarily “realistic” skin, but skin that looked good for MY project.
What follows is a basic roundup of the elements needed for good looking skin in 3D. Node setup will be shown at the bottom.
ROCK BOTTOM NECESSITIES
1. Texture Map
This can be really important. Not all skin texture maps are created equal. A great node setup with one texture set may not yield the same results when you try it with a new texture.
The model and texture I’m using for this post are from the Daz Victoria 5 model, available for purchase at the link to the Daz Website.
Since I primarily start my projects with Daz Studio, I buy a lot of the textures from that site, and also Daz/Poser market sites like Renderosity.
2. Bump Map
To keep your skin from looking like a perfect smooth mannequin, you’ll definitely have to have a good bump map.
3. Spec Map
Better texture packs come with a specularity map to help control highlights and otherwise map out which parts of the skin react in what way to the light.
4. SubSurface Scattering Map
I don’t usually find a specific SubSurface Scattering map in all the map packs I use, but if I don’t have one, I’ll just plug the diffuse map into the SSS node and tint the color to an appropriate shade for the character I’m using.
These next items aren’t always necessary, but can enhance the skin a bit. You’d have to give it a shot to see if it helps your image.
5. Translucency Map
I’ve only had a few cases where a translucency skin map was supplied. I used it because it was there, but most of the time I can get good results without it.
6. Displacement Map
Where the bump map fakes differences in height in your mesh, the displacement map actually does distort your mesh. Sometimes I might get a separate displacement map, or other times I see the bump map is expected to be used as both bump and displacement. In my testing it never mattered enough which was used, as there wasn’t much (if any) perceptible difference. I supposed if you have extreme close-ups it could be necessary to use displacement maps.
7. Velvet Shader
I have to say, I never had much use for Velvet. It’s a shader that’s supposed to simulate the effects of fine body hair. Whenever I add this node in, I never like the results so I always leave it out. I only mention it here since everyone has different tastes and goals, and mixing in a Velvet shader could be the key to achieving the look they were after.
Here’s a screenshot of the Blender node setup I was using for this image:
And here are the Daz Studio Values of the Surfaces tab:
You can see in my Blender screenshot that I have 5 image textures. I’ll always start with the color values from the Daz Studio Surfaces tab, but sometimes I might adjust them later. I’ve called them out in the image since you can’t see them when the textures are plugged in. Let’s take it from the top:
- Diffuse: This is my base skin texture, it’s plugged into the Diffuse Shader. Normally this color will be set to white, but if you need to tint or otherwise influence the texture map you can change the color. Sometimes the Daz color will be different, too. I find it best to start with the Daz value and only change if I don’t like the results.
- Subsurface Scattering: You can see this texture is plugged right into a Subsurface Scattering Shader. I’ve found the key with the SSS values is you need to start out extremely low. Blender usually defaults to a Scale value of 1.0 in the SSS Shader, but I will only start at a value of 0.1. Even this can be too high sometimes, but you’ll need to check the results yourself.
- Translucency: Translucency texture is plugged into a Translucent Shader. Not all maps will come with a translucency map. If you don’t have one, then don’t worry about it. Or if you really feel you need one, you can make your own and plug it in here. You would just use your original texture UV Map as a base, then make a black and white version where white is more translucent and black is less translucent, similar to a bump map. You can see there are no options to set for the Translucent Shader aside from the color, so just plug in and go.
- Specular: This texture is the spec map provided with the Daz Studio model. You’ll notice that it’s plugged into two Glossy Shaders. That’s because Daz uses a “Specular” and “Specular 2″ value which usually uses the same map. Look carefully though because some of the higher end models actually do have two spec maps. I’ll try to gauge the intensity of the spec map by checking the Daz strength value, then approximating it using the Mix Shader.
Meaning that if the strength for Spec2 is 30% in Daz, I’ll set the Mix Shader Fac to .3 so it only uses 30% of the bottom Shader. That means the top spec map is at 70% strength in Blender, which isn’t always the case in Daz. In fact, Daz has the main spec set for 55% in this case. In Blender I could reduce the intensity of the spec map by adding a Color Mix RGB Node (Shift A > Color > MixRGB) in between the Image Texture and the Glossy Shader, then changing the mode to Multiply and darkening the color from white to gray. I usually don’t do this unless the spec is just out of control, though.
- Bump: At number 5 we have the Bump texture. In this setup, I added the bump by using a Math Node (Shift A > Converter > Math), then plugging the texture into the bottom, setting the Fac to a very low value, then plugging it into the Displacement input of the Material Output node.
However, these days I use the Bump Node (Shift A > Vector > Bump) instead. What you do is plug the color output of the bump Image Texture into the Height input of the Bump Node. Then you connect the Bump’s Normal output to the Normal input of every shader your Image Textures are connected to. Here’s a screenshot of what it would look like:
To be clear, the skin renders you’re seeing in this article were done using the Displacement method, though. Not the second Bump Node method. It’s up to you to determine which is the better looking option for your scenes.
A couple of other things to call attention to:
Mix Shaders: The Mix Shader at number 6 is set to a Fac value of .7. This means the Subsurface Scattering Shader connected to the bottom input is set to a 70% value. This seems like a lot when considering my earlier advice about coming in very low at first when using SSS. However, if we check the values of the next Mix Shader at number 7 in the image, it’s Fac value is set to .2. Since the Mix Shader with the SSS input is plugged into the bottom, that means it’s only allowed 20% strength, while the Diffuse Shader in the top input will be allowed 80% strength.
From here, all we need to do is combine this Mix Node with the Glossy Nodes using yet another Mix Node set to .5, and we can wrap it up by plugging that into the Surface input of the Material Output.
I used a very basic lighting setup to get these results. Essentially a 3 point system using mesh lights made up of simple planes with an Emission Shader attached to them. Here’s a screenshot to show the setup:
I know there’s some people who shy away from using Ambient Occlusion (AO) lighting because it really doesn’t exist in reality.
From the Blender Wiki page:
There is no such thing as AO in real life; AO is a specific not-physically-accurate (but generally nice-looking) rendering trick. It basically samples a hemisphere around each point on the face, sees what proportion of that hemisphere is occluded by other geometry, and shades the pixel accordingly.
Read the rest here: http://wiki.blender.org/index.php/Doc:2.6/Manual/Lighting/Ambient_Occlusion
Anyway, I often use it because I like the look it gives me. If you want true photorealism you’ll likely forego using AO. I’m usually not looking to get that kind of result, so it works fine for me.
Using AO will usually make your scene a lot brighter, so you may have to reduce the intensity of your actual lights. Also, using Ambient Occlusion will increase your render times, so be aware of that.
You turn on Ambient Occlusion in the World Panel of the Properties view by simply checking the “Ambient Occlusion” box. Again, see the Blender Wiki link for more info.
Finally, the last trick up my sleeve is to use different film settings for the skin.
“Film settings??”, you say?
Yes, indeed. Blender can simulate the look of a variety of cameras. The way to activate this feature is to switch into your Scene tab, then open up the Color Management section. In here you’ll click the “Film” button, and then you’ll see a drop-down menu labeled “Look” at the bottom of the Color Management window.
You can leave the “Look” dropdown set to “None” for a generic film effect, or choose one of the many, many camera options for an approximation of that look.
Here’s some examples of different film looks:
WRAPPING IT UP
As a final comparison, here’s an image showing a default Daz render of Victoria 5 on the left, and the same Blender Cycles render from the top of this page, using the settings shown in the article.
Although you won’t win any awards with this basic skin setup, it will at least serve as a diagram of the elements you’ll need to have in order to create something exceptional.
Let me know in the comments or by social media, etc if you have any questions, and happy Blending…