A Guide to Skin Material With ZBrush and Single Pass BPR PabloMunozG

A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

a guide to

skin material

in zbrush & single pass bpr

by Pablo Munoz Gomez

BONUS repurposing the SKIN MTL for rendering

creatures

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Including resources

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A Guide to Skin Material in Zrbush & Single Pass BPR

Introduction

by Pablo Munoz Gomez

acne: pimples, blemishes, etc.

I know I have kept you waiting for this tutorial for a while but I took my time because I wanted to give you guys a quality tutorial that you can easily follow. Like my previous two eBooks: Creating dreadlocks with fibermesh and Wet Clay material; this new tutorial is also for an intermediate level user. However I do go over some main things in detail and if you are an experienced user you can follow the highlighted words and phrases that alone should give you a good understanding of my workflow. Let’s get started!

Research I didn’t want to bore you too much with the research behind this tutorial so I decided to filter the information into what I consider to be the most relevant bits.

Dry: Thin almost invisible pores Dull and rough prompt to crack and peel... more wrinkles

Skin types I have used many skin types in this project as well as making new skin types by mixing several of the ones I have made. For practical purposes, I will mention the two fundamental types: dry and oily. When working in ZBrush I used to think that dry skin needed a diffuse shader and for the oily skin I could just throw a specular shader on top to make it shiny. Well, in some cases that simple approach could work but it won’t get very realistic results, there are a few other differences between these types of skin, apart from the specularity. Oily skin is thick, usually has visible large pores and is often regarded as bad skin because of an excessive production of sebum (natural skin lubricant), which causes shininess and pimples. Oily skin is also less prompt to wrinkles. Dry skin usually looks tight and is prompt to crack and peel due to a lack of sebum (lubricant). It also has a slower cellular renewal process which means that the cells do not repair as fast, making the epidermis thinner (more on this later). Also, you can see “reddish” spots more clearly. The above descriptions are concise but the main things we need to know from each type are: Oily: Thick large pores shiny less wrinkles

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OK, so why is all of this important or relevant to this tutorial? Well, since the idea is to create a realistic type of skin (whether it is human or creature skin), taking into account the characteristics of the skin type will help us push the believability factor even further. This way we can avoid things that realistically won’t make much sense in general, for example, modelling an old man’s face with a lot of wrinkles, pimples and skin bumps everywhere and then applying a very oily shader to it (this would end up being a mix of the different properties of the two types of skin and that is not realistic). Tip: If you are modelling a face with large pores and skin bumps, they are less likely to be located around the eyes and neck.

Skin Layers Chances are you have probably used or heard about

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A Guide to Skin Material in Zrbush & Single Pass BPR this, especially if you have worked with subsurface scattering materials. Let’s see how knowing these skin layers will help us with ZBrush BPR render. There are 3 main layers: Epidermis: Outer layer - the surface Dermis: Middle thicker layer - layer of connective tissue Hypodermis: Inner layer - mostly the fat storage

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this is a property that in nature, almost all materials have (to different degrees). The way it works (in a very simplified way) is that when the rays of light hit the surfaces of a material, a portion of the rays is reflected and another portions is absorbed.  The light rays that are absorbed by the material, are “distributed” inside the object in various directions before exiting it - this is an easy way to think about the term scattering and all this, happens under the surfaces of the object so clearly Sub-Surface is a good name for it.   The rays of light that exit the object, after being scattered, are what we see and because they have been passing through the material, we get a taste of what is inside the material (sort of). What is inside the skin material is exactly the same for every person regardless of their skin colour or the type of their skin. I will super simplify it for you - just call it is BLOOD. 

If you are familiar with renderers such as Mental Ray, V-ray, Arnol, etc., you probably know that is standard to have 3 layers or 3 maps like these ones: 

Understanding this will make it easier for you to create all sort of materials with SSS, ranging from a wax statue to an alien creature with green skin and blue blood, not just human skin. Now let’s simplify the concept of the 3 Layers of the skin even more. From this point onwards, and for the purpose of this tutorial, I will just use two terms Inner (Dermis and hypodermis) and Outer (epidermis) and you can think of them as the blood inside and the skin surface. You will get a better grasp of this when we go through the practical stuff. I just wanted to share a bit of the theory in the way I assimilate it.

Skin pigmentation These three maps helped me to create something like this: Knowing this is very useful and when implemented correctly, it give amazing results. The way that ZBrush does SSS is a bit differently though, so let’s see if I can explain how SSS works a bit better: First let’s get the meaning of SSS out of the way. SSS stands for Sub-Surface Scattering, and

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Skin colour is mainly determined by a substance called Melanin and basically the more of this substance that a body produces, the darker the skin will be. Of course this is the result of natural selection and in a great deal to protect the body from Ultra Violet rays. The dark skin protects the body from UV rays much better than lighter skin.  There is an interesting article that you can read if you’re interested about pigmentation, it is a bit dense but it help me to understand a couple of things: Zonios, George., Bykowski, Julie., and Kollias, Nikiforos. (2001) Skin Melanin, Hemoglobin, and Light Scattering Properties can be Quantitatively Assessed In Vivo Using Diffuse Reflectance Spectroscopy, Journal of Investigative Dermatology, 117, 1452–1457. For this tutorial, here is what I think is useful: Dark-skin protects the body better than the light-skin from the UV rays. 

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A Guide to Skin Material in Zrbush & Single Pass BPR The way I interpret this information in practical terms, it might be not entirely accurate but, I think it works: the Melanin substance hels the skin to provides protection from ultra violet rays so is like a “shield”. The sun rays bounce when they hit the surface of the skin, so the more protection a skin colour has (in darker skin), the more rays that will bounce; the less protection in the skin (in lighter skin) the more rays will go through. With this in mind, let’s summaries the key features of each pigmentation: Dark skin has a “stronger shield”: More rays bounce from the surface - more specular Less rays that can go through - more subtle SSS effect 

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Main features that need to be reproduced to create a realistic skin shader Here I will just quickly summaries a list of skin features that I think are essential to achieve a realistic render. Diffuse (texture, colour) Secularity (shiny, oily) Translucency (SSS) Building up a skin material and setting up a render in ZBrush is much easier if you treat the characteristics of the skin as steps of a process, so I would start with diffuse as step 1, followed by specularity (step 2) and finally the SSS (step 3). This will make more sense soon when you get to that part of the tutorial.

I hope I haven’t confused you or bored you too much by this point, either way I think the next part of the tutorial will paint a clearer picture.  

About BPR render ZBrush Gives you the option to render with Best, Preview, fast and flat. The BPR (Best-Preview Render) gives the best quality for 3D models (in edit mode) and this is what we will be using. Light skin has a “weaker shield”: Absorbs more sun rays - more diffused light More rays that can go through - stronger SSS effect 

It is good to know that although the idea of this tutorial is create a good looking single pass render, the BPR render will always render each pass separately (as long as you turn it on from the BPR passes). You can tweak your image further after rendering it anyway.  The reason I use BPR over the other methods is that it gives me a lot of control when creating each pass and also when adjusting the image all within ZBrush. NOTE: For a lot of the images I create, I definitely like to tweak the passes separately and do the compositing in Photoshop (I also enjoy the compositing process a lot). The single BPR pass, however, gives me a fast and nice looking render that I can quickly fine tune without leaving ZBrush. It also allows me to create nice turntables and dish out multiple angles of a single model very very quickly.

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

Creating the Skin Material

You are probably familiar with this but let’s take a look at it anyway to understand how this works could help you enhance the effect of realistic skin with the BPR single pass.

We are getting closer to the good stuff, so in this section I will guide you thought my process of creating materials in ZBrush. If you have read my previous tutorial on WET CLAY, you might already have an insight on my work-flow, therefore the intro to the materials section in this tutorial will be brief (you can refer back to the WET CLAY tutorial if you want, because the process of creating a material is the same). 

The Wax Preview is very cool, I like it because you can see the effect in real time while you are modelling and if you know how to tweak it, you could get a very nice looking skin material with nothing more than this. However, sometimes the Wax Preview render could work against you. I have seen very nice and detailed sculptures that overuse the effect and end up loosing contrast and definition. 

Bottom line, this will be a step by step tutorial showing you how I created a very specific thing: A ZBrush skin shader for single pass render using BestPreview Render.  What this means is that this method will probably give you great results when rendering skin with ZBrush BPR, but it might not be the ideal material to use during the modelling phase or to render other type of materials.

In this following section, I will show you some practical examples of each one of the attributes for the wax preview render. If you would like to test this yourself as you read it, make sure you turn it on from the render properties AND make sure that the strength slider from the materials wax modifier is more than 0.

Why ZBrush Materials instead of Matcaps OK, for the skin shader I used a standard ZBrush material rather than making a skin MatCap for 3 main reasons: 1. I wanted full control on the different attributes of the material (i.e. diffuse and specular). 2. I wanted the material to react to the light rig I created.  Remember that MatCap (Material Capture) also captures the light so this is not ideal for what we are after. 3. I used a head model with Polypaint Texture so I didn’t want to affect that with any colour or diffuse information from a MatCap.

OK, let’s take a look at the wax modifiers... Wax (the real material), is a material that has a very strong SSS effect. You could potentially say that the stronger the SSS effect is, the closer the material is to wax. If we move the strength slider down a bit, you can tell that it is less waxy and it starts to look more like the SSS effect in the skin; a bit more subtle. The specular slider allows to add or remove the wax effect from the highlights, this is quite handy since you can subtlety add a fake SSS to some dark areas and transitions on your 3D model.

With all the testing that I have done with MatCaps and Standard Materials I realised that in most cases (and also depending on what effect you are after), when you tweaked a MatCap to the point you are happy with and then you added a colour or texture map, the result was somehow inconsistent. With a standard material, on the contrary, if a colourless model looks good with just the material, when a polypaint layer or texture is applied the render, will look much better! 

Understanding the Wax Preview

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Fresnel allows you to move the wax effect so it faces the camera or you can shift it to be angled away from

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

the camera. The exponent multiplys the intensity of the effect.

1. I like to work with small document while I create the shader so I can render it fast; I change my document size to: 1080 w X 720 h and drag the head tool onto the canvas. 

You can also combine the Fresnel effect with the Radius. The Radius allows you to spread the wax effect so if you set the value very low you end up with a very sharp effect.

2. The tool has polypaint which you won’t need at this point, so make sure it is off (not visible) and assign the model a Quadshader (at the bottom, from the material library).

The temperature is a nice effect that could be subtle but powerful. If you are making human skin, regardless of the pigmentation, the temperature should be hot or red simply because the blood is red. If you were making a fishy creature or alien that has a cold blue blood, you could change this to be cold and this will help create the effect. 

OK, so let’s keep it simple. The wax preview will be useful only after the skin shader is built to add an extra subtle effect but it won’t be the primary feature of the material. The idea here is that the effect will be achieved from the material channels and the way the shaders are mixed, you can therefore have extra control and a more accurate result. 

3. I also like to position the model on an angle that is not too close or too far (in distance), basically an angle that I can see the general shape and at the same time, judge how the shader looks with the details of the model. I also like to store that view and I suggest you do the same. In case you move the model, you can come back to the same position. This will be very handy later, when you are comparing the effects of the shaders. 

Building the skin Material OK, here is where the real fun begins! In this section I will show you step by step how I created a simple shader that, with a little tweaking, could give you very good results using the BPR. Open up a new document to start fresh and load the Pablander_head.ZTL, it should come up in the lowest subdivision level. If you want, you can use your own model, but I suggest you follow the tutorial with the model I shared, just so you can see precisely what I will show you through the steps and match the results you will be getting. This first steps do not need to be in this order but I usually start like this: 

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Now, before we continue there are a couple of things you might want to know (in case you don’t) about the QuadShader. First thing you will notice is that it looks like the model is overexposed, instinctively you may try to lower the intensity of the light BUT DONT! The shader looks like that by default. The 4 “slots” that make the shader are ON, so the effect of the shader is being multiplied by 4. And, the other thing you might notice

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A Guide to Skin Material in Zrbush & Single Pass BPR is that the attributes of the QuadShader are the same as the ZBrush default SkinShade4, so why is the QuadShader more suitable for what we are trying to do? Well, put it this way: you can tweak the SkinShade4 and get pretty good results already so with the QuadShader you have 4 times more control. This will make more sense as we progress. Also to avoid confusion I will refer to the QuadShader, from now on, as Skin Material, because each one of the “Slots” inside the Material are actually Shaders. 4. Go ahead and open up the left tray dock in the Materials palette and expand the modifiers of the material, turn off the shaders, one at a time, and you will see the effect getting less and less strong. 

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Turn off all the shaders except the first one, I will only talk about the shader attributes necessary to create this skin material but if you want a bit more info of what each one of the sliders do, check the ZBrush documentation or my previous tutorial that talks about the wet clay material. Set the Ambient slider between 20 to 25 and the diffuse all the way to 100. The idea is that this Shader 1 is going to be the colour/ texture of our material. Also, for this shader, I tweaked the diffuse curve to look like this. Just click on the curve to create a point and drag it, this is a tiny little trick that will add a little bit of “fake SSS”. Basically, you are editing the fall-off of the shader, so with a curve shaped like this, you will get less contrast on the detailed areas of your models. The reason I said is a fake SSS effect, is because with a fall-off like this you get less shadows and less shadows could suggest that more light is passing through, filling the little areas like pores and bumps and therefore suggesting the SSS effect (very basic but it all adds up towards the final material). NOTE: by the same principle, if you invert the shape of the diffuse curve, you get a “velvet” type shader or exaggerating the same curve shape you get the “posterise” effect. (Ambient set to 0 for these examples):

OK, that’s about it for setting up the project. I suggest you save and let’s start building the Skin Material.

Creating the diffuse shader  For the diffuse shader, I’ll be using the first shader of the material (first from left to right), the order of the shaders is important because the way we are going to mix them.

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

Let’s try to keep things as simple as possible, so the last thing I changed for the diffuse shader was the specular: I gave it 2 points in the specular slider and tweaked the curve to be smoother: I also like the specular colour to always be white. To do this, I changed the colorise specular slider to be 100 and selected white for the specular colour. Finally, I added a bit to the high dynamic range modifier.  You might notice that the model looks overexposed, almost as white as it was when you first applied the Quadshader. Don’t panic, this is intentional, turn on the polypaint by clicking on Colorise. You’ll see that the texture looks OK on the model. Leave it on for now, and we just need to tweak a couple more of sliders that I’ve found to be very useful, but are not that popular. They are the Anisotropic Diffuse and the Anisotropic Specular, you can easily achieve the same velvet effect I mentioned earlier by changing this attribute because what it does, is shift the effect of the diffuse (or specular) shader across the model. So, 0 means there is no effect and 100 means is completely inverted, I left the Anisotropic Diffuse at 0.28 and the Anisotropic Specular at 0.19.

You won’t see much difference by changing the specular slider because we only added 2 points to the slider, so it will be very subtle.  That’s it for the first shader, 3 more to go. If you hit BPR right now you should get something like this: 

This is exactly what we need to see at this point, almost a flat texture with not a lot of shadows and very few contrast areas. Kind of an in-between a contrasted diffuse shader and a completely flat shader.

Creating the Specular shader I mentioned earlier the main features I think are necessary to reproduce the realistic skin, so the next one on the list is specularity and for the purpose of this tutorial, I will try to create a generic “specular”. What I mean by that, is that it will be in the middle of dry skin

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

type and oily skin type (this way you can save a generic material that is easier to tweak depending on the nature of your future projects). The specular or “shininess” of the skin is achieve by adding a specular shader to our current material, which so far has the diffuse shader we just built and 3 more generic shaders. First, let’s set up the model so we can easily judge the contribution of the specular by itself... Turn off polypaint, turn off the diffuse shader (click on the little dot from the slot 1 of the material) and turn on the shader 3. The shader 3 will be the specular we are going to keep shader 4 for the SSS contributions and shader 2 for an extra cool effect. So you should have something like this again:

From this shader we are only interested in the specular. Go ahead and slide the ambient and diffuse attributes down to 0. 

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

Great you should have a black model with some shiny white bits, this is what we are after because the idea is to modify JUST the specularity and “nothing else matters” (for this shader). However, you might notice that the model is not completely black and some volumes are still recognisable, this is because by default, the ambient light from the light palette should be on. We haven’t got into lights yet, but for now turn it to 0 too. 

more trick I would like to share with you, and it’s again using the Anisotropic Specular slider.

Now we are going to use the specular slider to determine the intensity of the shiny bits and the specular curve to define how “oily” or how “dry” the skin is going to be.

OK, last but not least, we need to define the way our specular shader is going to interact with the previously created diffuse shader.

Zoom into the model and change the values of the slider up or down to see the effect, this is just shifting the material’s specular but be careful not to overdo it, this needs to be very subtle. Here is a comparison between 0 and the value I decide to use.

Go back to the front view you set at the beginning... Document > ZAppLink Properties > Front. Let’s turn the Polypaint back on and also the diffuse shader (shader 1). Hit BPR. Suddenly the specular effect looks too strong right? Well that is because we haven’t set the way shader 3 is being mixed. The Mixer sub-palette is where you can control how the shaders from a material interact or blend with each other. It sits just below the modifiers sub-palette from the materials palette, shift + click on it to expand the mixer and keeping the modifier still visible. Make sure you have the specular shader still selected since the mixer properties are unique to each shader.

So let’s try to get something that is half oily and half dry. For this model this is the value of specular and the shape of the curve that I think works nicely. This is pretty much what we need from this shader. However, there is 1

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A Guide to Skin Material in Zrbush & Single Pass BPR I’ll explain a bit more what the different sliders from the mixer are, but for now we are only interested in the blending mode. If you are familiar with Photoshop and I assume you are, you will see that the blending modes are almost the same as the Photoshop layers blending modes... If you were to take a single render of the diffuse we created and a single render from the specular we created and composite those passes in Photoshop by setting the blending mode to Screen for the specular layer, you will get something like this:

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areas so the rest can go). Try rendering it again you should see the difference straight away… And, that’s it for the specular contribution, you might want to change the shininess of the shader later on but for now is good enough to move on to the next shader.

Diffuse and Specular recap  I hope everything makes sense so far, but just in case I want to do a recap of the two shaders we have created to simplify the process even more, now that you have a better understanding of what they are and how they interact with each other: We have used a QuadShader material with 4 slots (shaders) and we have used only 2 of those shaders that form the Material: Shader 1 being the Diffuse and shader 3 being the specular. We set the mixer properties of the specular to be screen and enabled the “black” button so at this point if we render we should get something that looks like this:

It is very subtle again but when creating materials it’s all about subtlety, hopefully you can see the specular effect here:

From the Mixer sub-Pallet change the blending model to Screen just as you would in Photoshop. Try rendering right now and see what happens... The model looks super white, to fix this you need to enable the little attribute box next to the blending modes called “black” to tell ZBrush we want to apply this specular shader (or pass if you are thinking in Photoshop layers) on its own without blending it with any other shaders... we only need the specular information (the white shiny

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I would say that here we finish with the basic part of the tutorial and we are ready to move on to the advanced second part of building a skin material for BPR in a single pass.

Creating the Sub-Surface Shader The SSS shader will give the material the third main feature I described earlier: Translucency. This effect is

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A Guide to Skin Material in Zrbush & Single Pass BPR a bit more complicated than the two shaders we have already made, but I hope this guide will provide you with an understanding of how to manipulate and leverage the power of this effect within ZBrush. Before, we get started let me say a few things about the SSS shader: It will vary from model to model, so if you are using your own head/object to follow this tutorial you will get different results. It’s an effect that is dependent on more than just the shader, which means you need to take into account the light, the material modifiers and the render properties. There is not a magic number or formula that gives perfect and/or consistent result, so you WILL have to tweak the SSS settings when using the material with another model as well as in other projects.

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shader 4 and click PasteSH. Cool, before anything else, it would be a good idea to save the material (or the project if you want) and give it a proper name. From the material library simple click on save and give it a name. Also, to speed things up a bit, since we are going to be dealing with render settings, light and material modifiers, I suggest you dock the light and render palettes to the right tray so you get something like this:

Having said that, I will mention what I found to be the most relevant attributes needed to achieve a good result across a variety of lighting set ups and models. I will provide the steps necessary to set up the material in a way that it is easy to customise and change, so you can use it with other models too... The whole point of this tutorial is to help you speed up your workflow.  The first thing we need to do is grab the properties of a material that allow us to play with the inner and outer values (remember when I said I was going to simplify the skin layers dermis and epidermis into inner and outer? Well, here is what that concept comes into play). From the materials library find and select the FresnelOverlay material, then expand the modifiers, select the shader 2 and you will see that it doesn’t have much but it does have inner and outer sliders.

ZBrush allows you to copy and paste shaders between materials and this is what we need to do to make the SSS effect part of our skin material. Make sure you are in the second shader of the FresnelOverlay material and click CopySH.  Go back to the materials library and find the QuadShader you’ve been working on, select the

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You’ll also notice that I turned off the diffuse and specular and turned on the SSS (shader 4) so my model is just a black silhouette.  Let’s start with the shader modifiers. The best way to understand how it works is by testing, so at the bottom of the modifiers sub-palette you can see 4 squares or colour inputs, click on them and select a vibrant colour for each one of them: from left to right: Yellow, red, green and blue. You should already see some changes in the model but we need to set all the values to 0 so we can test the contribution of each slider separately, set everything to 0 and the Fresnel factor to at least 1 (so we can actually see the effects). OK, so the first two sliders are inner and outer additive which based on what I mentioned before will be equivalent to dermis and epidermis (not entirely accurate but it works for illustrating the concept). Here is where it gets a bit confusing, because when you

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

think about dermis and epidermis you probably think as layers with different thickness but the inner and outer attributes work based on the canvas view and the normals of your model, for example: in this sphere, I have set the inner value to 1 and left the outer to -1.

The next two sliders, Inner Blend and Outer Blend are actually the attributes of this shader that I prefer to use. The Inner Blend uses the same principle of the facing ratio but it blends the colour set in the InnerBlend picker, so if you move the slider to 1 you’ll see the effect:

And in this one I did the opposite.

In the same manner, if you reset the inner blend to 0 and move the outer blend to 1, you’ll see the same effect BUT with the facing ratio “inverted”.

Basically, forget about layers and think about facing ratio. The facing ratio is usually known as the Fresnel Effect and almost all materials in nature produce this effect to different degrees. Briefly speaking, the Fresnel Effect is a set of mathematical equations use to described how the light behaves when it travels between mediums with different IOR (Index of refraction). This effect is clearly visible in materials such as glass, water and/or metal. Let’s put things into context and see how using it can help the skin material we are building... One of the main features I listed before about the skin is obviously the Translucency, and the translucency is really the SSS effect (how the light is scattered in translucent materials). The FresnelOverlay shader we are using is the best option we have to recreate this effect since it allow us to play with the facing ratio for the material by tweaking its inner and outer values. In the skin material, the inner value will be “yellowish” while the outer will be “reddish”.

Keep in mind that these results are also depending on the number set in the Fresnel factor (currently set at 1), you can narrow the effect or make the outer and inner colour spread over the model even more by changing the Fresnel value. You can even invert the effect by setting negative values:

We’ll tweak these later, at the moment I’m just showing you what each attribute does... Now, look what happens if we set the inner additive to -1, the outer additive to 1 as well as setting the inner blend to 0 and the outer blend to 1:

I hope I haven’t confused you too much but let’s get on with the practical stuff... With a bit of practice this process will come as second nature when creating other materials.

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A Guide to Skin Material in Zrbush & Single Pass BPR Basically ZBrush is Blending the outer additive colour (red) with the outer blend colour (blue) making it purple. This is even more evident if you set the Fresnel factor to 0. So the reason I suggest to set the colours in this shader to such vibrant distinctive hues, is to be able to see the interaction between them. Blue and red makes purple and so on, feel free to try other combinations and you will get pretty cool results. I think you get the idea of what you could do with this shader, so let’s get back to the tutorial and onto the next step. Next, we are going to set the colours of the inner, outer and blends to be a more realistic flesh colour so I choose something like this:

We want the outer colours to be within the red hues and the inner colours to be yellowish. Once you set the colours, copy and paste the whole shader 4 into the shader 2. This is the extra effect I was talking about, which we will tweak it later. For now, just pass it into shader 2, turn it off and select shader 4 (SSS) again.

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Try making a BPR render after enabling the SSS.... Nothing happens right? Why not? We have tweaked the modifiers sliders, enabled the SSS in the light palette as well as the render properties, so what are we missing? Well, we have set everything in ZBrush for the SSS to happen, but we haven’t defined HOW the SSS shaders behave in the Skin Material (remember: when we set the blending mode of the specular shader (S3) to be screen and all that?). We need to go to the Mixer sub-palette for the SSS shader (S4) and tell ZBrush to MIX this shader as SSS by simply dragging the slider, conveniently called SSS, to 100.

Once you have done that, try BPR again and see if you finally start to get excited about this process.

OK, let’s put the outer blend slider to 1 and all the rest of the sliders back to 0, including the Fresnel effect. Hit the BPR button. You should get something that looks like this:

Wohoooo! We are getting closer! The following section will be about HOW to tweak the SSS from the render settings and the material modifiers.

Render settings SSS This is the SSS effect, but we can’t see it yet since we haven’t enabled any light to have the capability to render SSS. And, the render properties for SSS are also off; to enable them, simply click on the “SSS” buttons under the light sub-palette and the render properties palette.

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Now that we have the SSS effect working for us, we can start tweaking the settings from the render palette. What I usually do, is create a document in Photoshop and paste screenshots of the renders, so that every time I do something different in the settings I can check and compare the changes. I will guide you through what I have found to be the best settings for this particular project, so you don’t have to do any of that. From the render palette, expand the sub-palette called “BPR SSS”. The first thing you see, is a button that says SSS Across Subtools, click on it to enable it. This button determines how ZBrush will light up the subtools

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A Guide to Skin Material in Zrbush & Single Pass BPR as a whole (when is on), or individually (when is off). So if you have a model made out of multiple subtools, you should leave this ON unless you are after some particular look. Regardless of the number of subtools I have, I tend to just leave this ON. Next, you have the rays and the Angle attributes, these two are directly related. Basically, the higher the number of rays, the softer the SSS effect would be. Keep in mind that increasing the number of rays will increase the render time. At a glance, it might be hard to see the difference that these values have, but take a look at this contrasted image rendered with 1, 30 and 100 rays:

Obviously, 100 rays look much better than 30, but usually you don’t really need more than 50 rays. However, for the purpose of this tutorial, I will leave it set at 100 for best results (you’ll see why after reading the next couple of paragraphs). The Angle will affect how narrow the SSS effect is, based on the light source, the way I understand it, is that the value you set in the Angle slider will determine how much the SSS effect will spread around the model, taking into account the light position. For example, in these images, I set the Angle to 1 and to 360, and I moved the light source to the right.

When the Angle is set to 1, the effect is only visible along the edges of the model and when it is at 360, the effect spreads, reaching other areas of the models. Now you can see the nose and other volumes of the face. You could also think about this as how diffused the light source is. A value of 1 would be equivalent to something like a torch light (very narrow light source), and a value of 360, will be like a bright cloudy day (very diffused light, that covers a greater area, equally).

by Pablo Munoz Gomez

basically because the higher the number you set in the Angle value, the more Rays you may need to make the spread effect look smoother. Examples below:

I’m going to leave the Rays at 100 based on what I had said earlier, because I will use the Angle value of 360. This is not a must for the tutorial or SSS effect, this is just my preference as I will edit the light later to have more diffused shadows (if I wanted a more direct light with sharp shadows, I would probably lower the Angle value to accommodate the “lighting conditions”). Moving on, you have the Res value (Resolution) and the Blur. The resolution in pixels is linked to the size of the document you are working on. For the moment, I will leave the resolution as it is (at 400), but for final images will increase the number to something like 1000. You could go higher than that, but in most cases you get very good results without having to set crazy numbers here. The Blur is linked to the resolution and setting higher values will give a softer SSS effect. I don’t change the Blur too much, but feel free to test various options and see what works for your project.  Finally, you have the VDepth and the LDepth. OK, these two settings are very important to achieve the effect we want, so I will try to briefly explain them separately: VDepth (View Depth) will take the SSS effect that we have set up and offset it based on the view. Look at these 3 screenshots using different values:

You could think about this in the following way: Imagine the whole SSS effect is contained within an invisible layer or box, and when you change the value of the VDepth slider you are offsetting that container box, closer or further away from the view:

The reason that Rays are related to the Angle value is

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

NOTE: The front face of the box is facing directly towards the view of the document; the model is on an angle purely to demonstrate the offset of the SSS.  LDepth (Light Depth) also does the same but based on the light source. So, in the previous example, the imaginary box doesn’t move in the direction of the view but rather in a straight line between the model and the position of the light. In the images below, I have moved the light source exactly behind the model and tested the LDpeth with values of -100, 0 and 100. 

The mixer for the SSS shader Now that we have a general understanding of the render settings for the SSS we need to mix the shader with the diffuse and specular shaders. Before you turn them ON again to test the material, I want to clarify a couple of things… The SSS effect is very subtle in most scenarios but is present nonetheless, so you should judge how much of this effect you want to add to your render based on things like the intensity of the light source(s), the position of the lights, the thickness of the model, etc. The human head for example, will have varying strength of the SSS effect, depending on which part of the head the light goes through. The effect will be very strong along areas such as the ears and nose, but almost non-existent around the skull and other bonny areas.

Hopefully this image will serve as an overview of the VDepth and LDepth sliders:

Finally, you have a little button called “Spd” next to the LDepth, which stands for Sub-Pixel Depth, I usually leave it ON because it produces a more accurate SSS effect, but turning it OFF while testing stuff, will speed up your renders. 

If you do a render right now with the values I provided, you should get something that looks like the images below on the left. There is a lot of “spreading” into the skull, chin, cheekbones, etc. This is intentional FOR NOW because we will fine tune it from the mixer inside the material, to get something more like the image below on the right. 

OK, so let’s see how this was done using the mixer for this SSS shader. Open up the Mixer sub-palette and for this shader we are going to concentrate on only 2 attributes (that is all we need): The S Exp and blending mode.

To sum up, these are the best values I found to work for what I want to achieve:

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A Guide to Skin Material in Zrbush & Single Pass BPR Change the “S Exp” from 1 to 2. What this slider does, is change the falloff of the SSS effect so the more you increase the number, the narrower it will look, that is the reason I left the other settings to let the SSS spread quite a bit, so that we can control it from only one attribute in the mixer.  Now we need to change the blending mode from normal to add and turn on the Black button. That’s pretty much all we need to change here in the mixer.

by Pablo Munoz Gomez

achieve different looks (more on this in the bonus section), without altering the SSS or wax preview settings. 2. It adds an extra level of control when we tweak the filters in the rendering section. I made this shader in the exact same way that I created the shader 4 (luckily nothing needs to be altered in the render settings) so play with the sliders and get something that works for you. Like you see in the previous picture the main slider to change within the mixer is the Fresnel attribute. If you want the settings I used, here they are:

The extras effect - Shader 2  The Shader 2 or what I’ve been calling the “extra effect”, is simply another layer of sub-surface scattering. However is not dependent on the SSS properties from the render settings, since it’s actually based on the Fresnel slider within the mixer. Let me show you what I mean:

OK, this is more or less the process of creating the Skin material. In the next section I’ll cover Lighting, rendering and compositing (within ZBrush). But, before we move onto that part, I will add one final thing to our shader - that is the wax preview. To do that turn shaders 2, 3 and 4 OFF and shader 1 ON (our diffuse shader). With only that shader selected, go to wax modifiers (just above the materials modifiers) and set the strength to something like 50. Play with the Fresnel and Radius slider until you get something you are happy with. You can refer back to the Understanding the Wax Preview section earlier in the tutorial. These are the settings that I liked: The image above displays the effect of shader 4 (SSS effect) and shader 2 (Fresnel SSS fake). As you can see from the image on the right the effect is basically a red colour edge that defines the volumes of the model a bit better than what the shader 4 does. I found this extra effect to be extremely powerful for two main reasons:  1. It’s a middle ground between a full SSS and a wax preview and can be easily customized to

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A Guide to Skin Material in Zrbush & Single Pass BPR

Skin Material Recap Let’s see what we have so far. We created a Skin Material that uses/combines 4 shaders: 

by Pablo Munoz Gomez

lights; and, the rest are disabled. Go ahead and click the button to create a new light, you’ll get something like this:

Shader 1: diffuse shader and is relatively flat. Shader 2: fake SSS. Shader 3: specular shader. Shader 4: SSS effect. The way that all these shaders mix with each other and create the final look of the materials, is determined by the mixer in the material properties (and the render properties for the SSS). Below, are renders of each individual shader and then a combined version of the material:

If it doesn’t look too exciting yet, remember that this tutorial is about creating a skin material to render in a single pass using BPR, so we have only completed part of the process - setting up the material. Now, we need to dive into the rendering and lighting.

At this point I will recommend that you to turn OFF the SSS pass from the render properties to make the test renders faster while we set up the lights. Also turn OFF the primary light, so that you can see the effect from the LightCap on its own. Render the image and see what you get. Now, if you hover over the black box with the light on it you’ll see a red little dot, click on it and drag it towards left side of the box. The shape of a sphere will become more obvious, hit render and check the results.

Lighting and rendering   Now, that we have the skin material 95% ready (allowing 5% for other tweaks during the rendering steps), we need to set up the lights for the scene. At the moment there is only one light in the project, which is the KEY light casting shadows, with the SSS property enabled. In this tutorial, I won’t go too deep into the different types of lighting setups or why the light plays a big role in the final image, because that would be a whole new tutorial in itself. I will keep it simple and only have a 3 point light system. The 3 point light system is standard but it’s good for what we need right now. The 3 lights are usually: 1. Key lights (primary light source). 2. Fill light (generally a diffused light source placed on the opposite side to the key light source). 3. Rim or Hair light (a light placed at the back, to enhance the silhouette of the subject).  We already have our KEY light, and we can worry about the shadows later. To create the Fill and Rim light we are going to use the ZBrush LightCap which, in my opinion, speeds up the process a lot. Go to the Light palette and expand the LightCap subpalette, in it there are two buttons: diffuse and specular; and, a big black box, which is a preview of the lights and it’s black because there are no lights in it yet. Right below it, there is another button: New Light - to create

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Cool, you can see how the lights (red dots) you placed in the LightCap sub-palette are then translated to the scene, very closely to how they look in the black box. At this point, we are going to turn everything ON again, because now we need to judge how everything is going to look as a whole, not simply individually. So turn the SSS back ON from render properties as well as the primary light properties. From the LightCap sub-palette, once you create a light, you will get its attributes below the black box. Create another light by clicking new Light again and move this one to the right (you can use the “Light Index” to select and navigate between the lights).

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A Guide to Skin Material in Zrbush & Single Pass BPR If you render now, you should have something like this (if not, make sure the SSS in render properties and the primary light are enabled again):

by Pablo Munoz Gomez

The next step is to change the Falloff. This attribute determines how the light is distributed in the space, you can think about these properties as the shape of the light source - how wide or narrow the cone of the lamp is. Set the Rim light to a lower number like 0.4 and the Fill light to 5.5. For this render, I have also lowered the intensity of the main light (Key light) slightly from 0.85 to 0.72 and also added a bit of colour to the Fill light.

We need to get rid of the shadows from the Fill and the Rim light, in the LightCap sub-palette, change the Shadow slider to 0. At this point, I also changed the strength the Rim and Fill to 5 and 2.5 respectively.

Now the effect of these two lights is quite obvious but at the same time it is overly strong. We are going to tweak each light separately to get a nice fill and back lighting effect. The aperture determines the diffuse and specular falloff of the light, in other words, how soft or how sharp the light blends with the dark areas. A number of 1 will give you very narrow lights and a number of 180 will be a very diffused light source. From the LightCap settings, change the aperture of the Rim light (the first one on the left), to something between 40 and 50. And, for the second light change the value of it to 100. This way you are telling ZBrush that you want the light source 1 to be quite narrow (to simulate the Rim light) and the light source 2 to spread over the model a bit more.

Hopefully you can now see some of the effect of the Skin Material working nicely with the light setup. The next thing I want to do is get rid of those strong shadows coming from the KEY light and make them more diffused. That is achieved through the render settings. For this reason, I like to treat Lighting and rendering as one section. Open up the render palette and we are going to tweak the BPR shadow:

The first two sliders FStrenght and GStrenght control how strong the shadows are, FStrenght is only concerned with the casted shadows on the floor. By turning it to 0.01 you won’t see much difference (unless you have a floor). The GStrenght on the other hand, deals with the intensity of the shadows on a global scale. What this means, is that you can change these sliders and this will affect the shadows’ strength of each shader. Huh? Shadows for each shader? What?  OK, so there is something else I didn’t mention during

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

the material creation which is the environment sub-palette. The reason I avoided it was because it is more relevant now that we are dealing with rendering settings and also, because it is awesome! So simple, but so powerful. Let me explain:

Environment Sub-Palette In the same way each individual shader we created has options in the mixer sub-palette, they also have an area called Environment that has 3 simple options: Shadow, Ao and vibrant shadows and AO. These attributes are unique to each shader and the Shadow and Ao slider refer to the strength of those features for each shader. Maybe an image will illustrate better what I mean. Here are the 4 renders - I switched the Shadow slider to 0 for each one of the shaders that make up our skin material:

Perhaps the image above gave you a better idea, but if not, I want to explain this in a different way BECAUSE I really want you to understand these Environment settings. If you didn’t know about it, this is probably the best TIP you will get out of this tutorial. I’m serious! It blew my mind when I found out about it. It will slightly change the final look of your renders but you will definitely see the difference in many ways. TIP: Each one of the shaders we created have different properties and different ways that they mix with each other in order to create the Skin material, but they all react to the light in the same way (to some extent). The Environment sub-palette allows you to change the intensity of the shadows for each shader that make up the material INDIVIDUALLY. The reason I think this is very powerful, is because it lets you “mask out” or lower the influence of the SSS shader shadows, for example. I can still get the shadows I need but wherever the effect of the SSS is, the shadows will be less prominent, enhancing the overall look of the render. Take a look at how it works with practical examples, for image A, I took our KEY light and placed it behind the model and left all shader environment shadows at 100. For image B, I simply changed the environment shadows of the specular to a lower number (83) and the SSS shader to 0 nothing else:

So you see how different the renders are and how much more realistic the image B is. In the same way you can change the Ao (ambient occlusion if it’s enabled from render settings) slider, to affect each material.

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A Guide to Skin Material in Zrbush & Single Pass BPR Finally, the button called Vibrant Shadows and AO if turned ON, will give you a vibrant saturated shadow. If you have ever rendered an image that looks like the shadows are “burning” or are red towards the edges, here is how you turn that effect OFF. Back to the shadow render settings... Now that you know that the Environment shadows slider works for each shader individually, it’s easy to understand what the GStrenght does. Basically, it lowers the intensity the shadows on a global scale:

by Pablo Munoz Gomez

The attributes below rays and angle: Res (Resolution); Blur; VDepth and LDepth; those were covered in section discussing the BPR SSS sub-palette. These work in the same way. The rest of the settings I generally don’t touch, but it is worth mentioning a couple of these briefly, in case you want to tweak them: Gamma: this slider will change the “gradient” effect between the areas that have shadows and the areas that don’t get shadows, lower numbers mean almost no gradient and higher numbers refer to almost no shadows. Falloff: works in junction with the Gamma slider, you won’t see much difference unless the gamma is set to 1 or lower. I haven’t noticed this to make much of a difference (like I said, I barely touch these settings... for me is just good enough to know they are there). Max Dist: this slider will change how “far” or how “close” the shadow will cast.  DistFalloff: works with the Max Dist slider and will change the speed of the shadow’s falloff.  

Final tweaks to the material The shadow Global Strength slider value is really up to you, and it may vary depending on the look you are seeking to achieve. For example, a lower value will suggest brighter environments, but a strength of 1 could suggest a very dark environment:

Go ahead and do a best preview render of what we have so far and let’s see what works and what can be improved.

From the render, I can see 3 things that are not quite right:  The next sliders are Rays and Angle which work in the same way as the counterparts from the BPR SSS sub-palette previously discussed so I won’t get into the details here. Just a quick tip: when you set the Angle to a high value, you should then increase the number of rays too in order to retain a good quality render. In this tutorial, I have set the Rays to 60 (I will change this value to 120 for final render). An angle of 90 seemed to work well to achieve the look I was going for.

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1. The SSS effect on the ears is maybe too strong and the red looks like it is almost emitting light. FIX: From the mixer, I changed the blending mode from “add” to “screen” that makes the whole SSS contribution less bright.  2. The fake SSS from shader 2 has a very saturated red and is overriding some shadows.  FIX: Select the shader 2 and from the Environment sub-palette, turn OFF the “Vibrant Shadow and AO”. Also, in my case, I wanted to spread the effect of this

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A Guide to Skin Material in Zrbush & Single Pass BPR shader a bit more from the edges, so I changed the F exp value in the mixer from 1.1 to 0.8 3. There are some “stepping” in the shadows cast by the chin. FIX: As I mentioned earlier, for the final render I will change the shadow rays from 60 to 120, and that should do the trick. One more thing: I thought the specular needed to be slightly more visible so I increased the specular value.  Here is a render test with the tweaked material:

by Pablo Munoz Gomez

Render, filters and Adjustments The final stage, this is my favourite part (along with the sculpting!). When everything has been set up and the model is ready to render, I can spend a lot of time fiddling with the layers and passes. I always do some sort of post production to my images. I treat my renders as my RAW images, so I always do some sort of colour correction, or curves adjustments, split toning, etc. I would usually export my passes separately from ZBrush and do the compositing in Photoshop. but this tutorial is about creating a workflow for a quick and nice render, all within ZBrush (that is why we initially spent some time setting up the skin material so that when we hit render, ZBrush would combine the shaders as passes), we therefore can bypass the compositing in Photoshop. Fortunately, ZBrush also allows us to do some final adjustments and refinements to the image after the render, by using filters and adjustments. 

Render At this point I will edit the size of the document to get a larger image. Go to Document, and change the I think it looks much better now, remember that when dealing with materials, subtlety is key. Finally, before getting into compositing with ZBrush I like to move my light around and make various renders to test the consistency of the material:

dimensions to suit your needs, I changed mine to: Position your model in its final pose or whatever angle you like to do a render. I chose a very generic and straight pose just for the purpose of this tutorial, but you should be able to get a more interesting shot.  One last thing I like to do before rendering is to change the camera angle, so that I get a more photographic effect given that my camera position is quite close to the subject and therefore the “lens” of my camera will distort the perspective a bit. You can achieve this from the Draw menu, by simply

changing the slider called “Angle of View”. That’s it! Hit render and we can start with the filters.

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A Guide to Skin Material in Zrbush & Single Pass BPR

Filters If you are familiar with Photoshop, filters in ZBrush, are like the different adjustments you can find in Photoshop. One of my mentors once told me that “masking is the backbone of the technical aspects of compositing” and through my experience, I have to say that knowing this has helped me a lot. In Photoshop you can bring all your passes, start masking things OUT and blending all the layers to create your final image. In my opinion, the power of using filters inside ZBrush, relies on the capability of masking the effect of the filter by a wide range of attributes without having to create a mask or extra stuff.  Let’s start by opening the filters Sub-Palette within the render palette. The filters selection and switches (to turn them ON and OFF) are identical to the way we selected the shaders in the Skin Material and by default they are all OFF so let’s turn the first filer ON

by Pablo Munoz Gomez

The Filter Type: a drop down menu to select the type of filter you want. So for the first filter (F1), you can change the “noise” to be a “Hue” filter. In fact you can change all 12 Filter slots to be the same Hue if you want. Below, the filter type you have is the blending mode. This applies the same concept as the blending mode we had used when creating the shaders (or the layers blending mode in Photoshop). Filter Strength: will modify how strong the effect of the filter will be. Filter Opacity: control the overall opacity of the filter. Section B contains: All the sliders you are going to need to mix and mask the filters with the final images. This is one of those things that is better to see how it works, rather than read the theory behind it, so let’s get to it...

My filters workflow I like to start in order, that’s why I enabled the F1 and turn more filters ON as I go. As opposed to what I did with the Skin Material set up, where all shaders were turned OFF (except for the one I was tweaking), I like to see how the filters work together. The first filter is the noise effect, when you turn it OFF you see the effect immediately, that is another great thing, you don’t have to re-render every time you adjust a filter. The whole filter sub-palette looks a bit overwhelming at first because of the number of sliders it has, but once you get the hang of it, the level of control it provides, is fantastic. I won’t explain every single filter but I’m sure that with a general guide on how they work, you can figure out the rest for yourself. I divided this sub-palette in 2 sections to easily digest what the attributes are for. The sections are Filters A and Filters B.

First, I set the filter strength to 100 (in this case, F1 is noise) so I can see clearly what the filters do and how they are affecting the image. Then, I start playing with the sliders from section B to get what I want. I want to add noise over the whole image so I just want to tune down the noise strength and opacity. 

Section A contains:

The second thing I would like to do, is to sharpen some Areas of the render to enhance some of the details, like pores and imperfections, so I turn on the filter 3. (You can simply use the filter 2 and change the type to be Sharpen).

12 slots where you can add filters (so you can add up to 12 filters. I usually don’t use them all).

Like I said, I change the strength and opacity to a 100 and also change the Radius (first slider from section B) to 25. The Radius is the degree to which the effect of the filter is spreading.

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

effect very subtle but necessary. The rest of the filter... F4 - Orton: I use this to brighten up some areas at the back. I used the Depth slider to enhance only some of the areas away from the camera.

You can see the effect very well, but what I want now is to only to sharpen the areas that are closer to the camera. Here is where the masking I mentioned before, starts to shine. Change the Depth slider to something like 0.2. Basically, what we are doing is telling ZBrush to apply the Sharpen filter based on the “depth” pass, so the positive values will sharpen areas closer to the camera and the negative values will sharpen the parts of the model furthest from the camera.   You can also increase the Depth Exp to multiply the strength of the mask (narrow the effect). And these concepts apply for the rest the sliders from section B, so you can apply your filters using the SSS as mask or the Fresnel effect or Shadows, etc. I then tend to spend some time getting the right amount of strength, opacity and altering the radius of the filter:

F7 - Colorise: I like to use the colorise filter to add a bit of colour to my shadows. I set the blending mode to Screen, selected a blue colour from the colour picker and I also did a few things differently from previous filters:  1. I set the Mask slider to 1, this constrains the effect to the mask pass, so you won’t see the blue in the background of the canvas.  2. I want the colour to primarily affect the dark areas of the render, so in other words, I want to make the shadows a bit bluish rather than purely black. To do this, I use the Shadow slider. 3. I used the SSS slider with -1 this way I tell ZBrush I want to use the SSS pass as an inverted mask (because of the negative value) so that the colour blue ignores the areas were the SSS pass is stronger (like the ear on the left). 

For the rest of the filters, the workflow is the same, so let me summarise it. Then, I will simply show you the settings for the rest of the filters I use to get final image.

Recap: 1. Turn on the filter slot F#. 2. Select the type of filter you want. 3. Set strength and opacity to 100 and Radius to a higher number than 1 to see the effect of the filter. 4. Use the rest of the sliders to decide where and how the effect is applied.

F8 - Red: I use the red filter to slightly enhance the effect of the SSS. I used the Fresnel as mask to achieve those reddish soft borders and also only wherever the SSS pass is stronger.

5. Tweak the settings back to values that will make the

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A Guide to Skin Material in Zrbush & Single Pass BPR F9 - Red: I use another Red filter to add some colour to the details in the skin, such as pores. I use the Cavity slider to limit the filter to those areas.

by Pablo Munoz Gomez

There is not a massive difference but they do change some things. I reckon they help, in general, to make the skin in the render a bit softer and slightly brighter.

The adjustments

F10 - Blue: I use the blue filter to add some variations to the skin tones so that not all the areas are “red”. I basically played around with the masking values until I got something that I was happy with.

Alright we are getting closer to our final super setup. The last thing I want to show you is the Adjustment, the last sub-palette from the render palette. Click on the button called “Adjust” to enable the adjustments. By default, everything is set to 0 (except gamma that is 1), so you won’t see any immediate changes like when you turned ON a filter previously. This palette allows you to correct 3 things basically: 1 Contrast, 2 Brightness and 3 Gamma. But, it gives you a lot of control since you can tweak each individual channel Red, green and blue). By modifying all these values you are able to get some pretty cool results and split tone effects without leaving ZBrush:

F11 - Saturation: I use this filter to saturate the shadows just a bit, very subtle overall effect.

Also, you have curves at the bottom of the sub-palette and you can change the curves individually for Red, Green and blue. I tweaked the Adjustments a little bit, and managed to get something that looks good to me. Let’s compare the RAW render versus the final Composition with filters and adjustments:  That’s it for the filters, let’s compare the “RAW” render with the one with the filters applied...

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A Guide to Skin Material in Zrbush & Single Pass BPR Cool… I think I have covered most of the things I wanted to show you. The last tip or suggestion, is to use the filters and the adjustments to get something that you think looks cool, then step away from your computer, then come back, judge the overall image again and tune everything down a bit. Here is my final image, I changed the background colour, reworked on the adjustments and repositioned the light towards the centre.

by Pablo Munoz Gomez

Conclusion So the tutorial has ended up being quite long and it took me a while to put everything together, but hopefully it will give you a good insight into my workflow. It isn’t perfect or the only one by any means. If you are able to take something away from this, even just a tip to improve your art or speed up your process, then the time I put into this is well worth it.  I know we are all super excited about the upcoming ZBrush - Keyshot integration and that will supercharge all of our renders. However, I still think that ZBrush can produce amazing things as it is right now. This tutorial was never intended to replace a more elaborate work flow to produce higher quality images, but rather to provide you with the option to obtain multiple variations to choose from, without having to take your passes to an external editing package, and to do this within very short period of time (once you set everything up).  Keep in mind that every time you do a Best Preview Render, the individual passes are also being created. So if you want, you can take your quick render to Photoshop for further improvements, using the passes that ZBrush generates.  

Final Thoughts I really enjoyed creating the material and the setup as much as I liked writing the tutorial. I tried to keep everything very informal and casual because I write based on my notes that I take as I progress on my projects. However, if at some point you would like to know more about something in particular or need any help, feel free to contact me by email or on my Facebook page, if I can I will always be happy to help.

Now that we have completed the whole Material and rendering set up, you can generate as many renders as you like. Changing the angle of the shot and maybe the position of the light to get a more dramatic effect like these extra renders I made, all took under a minute each.

I’m working on something really cool and I’m very excited to say that it might be ready for early next year… I can’t say much at the moment but if you enjoyed this or any of my previous tutorials, you are probably going to like what is coming! You can follow me on Facebook and Twitter to keep up with my updates. Finally, I made this tutorial for the ZBrush community, so I encourage you to share it around your networks if you found it valuable and useful. The only thing I ask for, is to share the original link to the PDF not the actual PDF so I can track how well the tutorial is received in addition to directly receiving feedback from you guys, which will better mould the next tutorial. Please send me links to whatever you do using this method. I would love to see what you come up with and I will be happy to feature your work on my blog. I appreciate the Facebook page likes! All the best and happy ZBrushing!

www.pablander.com

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

Bonus Material As I promised here is an extra bit of tutorial where I show you how easy is to modified the material to suit other needs. I will be using an alien head which is just a quick Dynamesh sketch with polypaint and I will show you how I created this:

www.pablander.com

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

first I loaded the saved project from this tutorial and load my alien head as a Ztool with polypaint information. I followed pretty much the same steps I described at the beginning of the tutorial to set up the project, document size, etc. then I imported the material and open the Modifiers subpalette. This is the section I used to modify the material’s properties a bit to make it suitable for an alien skin. I change the settings for each shader individually, with the the diffuse shader on and the rest off, then the fake sss, then the specular and finally the SSS. For example with only the diffuse shader on this is how it looked with the material we previously created. But since the colour scheme for the creature is blue I changed the outer blend and additives to better match the tones of the polypaint just changing the colour pickers. And tweaking the sliders a bit.

And this is how it looks with minor tweaks. Mainly I tune the ambient down and reduce a bit of the specular and slightly changed the diffuse curve.

For the specular shader the render looked like this for this creature.

The fake sss or shader 2, looked like this with no alterations.

But I wanted to create a more “gooey” and wet so I tweaked the specularity curde and intensity as well as the fresnel slider from the mixer.

www.pablander.com

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A Guide to Skin Material in Zrbush & Single Pass BPR

by Pablo Munoz Gomez

I also wanted a more dramatic lighting so I changed the shadows to be a bit sharper and repositioned the light.

For the shader 4 (SSS) this is how the creature lookd with no tweaking And just by adjusting the inner and outer sliders, setting the colours to a blue tones, and the S exp from the mixer sub-palette I got something like this

finally I turn all the shaders ON to see how they look...

After getting the light source in the place I wanted, I simply started to add the filters and tweak the adjustments sliders to get this:

Like I said, you can always take the passes that the BPR generates and do some more tweaks... I took this guy into Photoshop but I only took the beauty pass, the mask and the depth and changed the background (that is why I needed the mask) and added a bit of depth of field (using the depth pass) and some really minor adjustments with the curves. All under 5 minutes including render from zbrush. So the material we created could be very easily altered to get all sort of skins types and even non-human skin. I hope you enjoyed this little bonus section and talk to you soon! Pablo Munoz G.

www.pablander.com

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