Over the past year I've focused on my Sculpting skills, this lead to me ignoring some of the other necessary skills necessary for good Character Art. To rectify this I did a deep-dive into creating realistic skin using ZBrush and Substance Painter, for rendering in Unreal Engine 4. Through this little series I'll be detailing how I made the Height, Diffuse, Roughness and Subsurface maps. As well as some experiments I did along the way.
When it comes to creating skin, or texturing any character model a good first step is height detail. Good height and normal details create the necessary bake data for our Diffuse and Roughness portions to be far more detailed, far easier.
Necessary Skin Details:
- Micro-creases/Skin Direction
- Necessary Variation
I will refrain from including too detailed reference images because they can get kinda gross.
EXPERIMENT: TEXTURING DETAILS VS SCULPTING DETAILS
Substance painter has a rather large collection of Skin Materials to be used on different parts of the body. These can range from something as small as lip details to something as large as back creases. When I started this project I decided to see how far I could get with these materials alone. Spoiler Alert: Not Very Far.
The process involves 3D projecting the tileable materials onto the mesh, increasing the tiling, and masking out where you want them to be. With the occasional 2D material needing to be translated to the right spot in UV space.
Here are the results of the face. It's kind of there but it doesn't fit on the face right. The pores around the nose area are too intense, even at 1% intensity. The pores and wrinkles here, even at higher resolution, don't look they have much direction or purpose. It just looks like noise in some areas. Creating good variation in pore size will fill up your layer stack quickly, something I'm not especially comfortable with. Overall, not a completely unexpected outcome.
QUALITY: These materials can only go so far. For the purposes I want, they simply don't go far enough. They're a pretty quick way to get something. They might come in useful to supplement any spots I miss when I sculpt these details.
COMFORTABILITY: The process of dragging in, changing the scale, changing the intensity and THEN masking out specific areas is one I find very clunky.
EFFICIENCY: These materials come built in. No need to go Alpha hunting on the Marketplace. For creating a base layer of Skin Pores or Skin Creases this is far quicker than creating it in a sculpting program, baking it, and then continuing to work in Substance Painter.
In contrast, ZBrush has very little skin resources built in. There's a couple things that Noisemaker can do but that suffers from similar drawbacks as texturing details above. This is 50% a process review, and 50% shill of J Hill's Skin Detail's Kit. I used the brushes there to create varied skin details of a consistent quality. Despite this, remember, the best alphas and brushes are useless in the hands of someone that doesn't know how to use them.
Sculpting these details by dragging out an alpha will immediately create some variation in Pore and Wrinkle Sizes, making our skin look far more natural. The difference here is subtle but enough, and we can immediately use our Mesh Maps to drive our skin details. There isn't much to say other than:
QUALITY: The overall quality is greater because I have more control over the Size and Intensity of these details. We don't have to worry about any tiling textures or scrolling through Substance Painter for us to add exactly what we want.
COMFORTABILITY: I sculpt everything as much as I can, so sculpting these details in Zbrush is essentially second nature. The only drawback I have is how many polygons are needed for these details to come through, I'm working on a decent laptop but even then it chugs when I get to a high resolution.
EFFICIENCY: This is where Substance has got Zbrush beat. At least for me, dragging out Zbrush Alphas and brushing in details takes longer than adjusting parameters and masking. Though we don't have to do any fiddling about with height-to-normal filters or anchor points for our height details to start driving our diffuse and roughness maps later down the line.
With that experiment over, let's get into HOW and WHY we can create proper height detail.
All these following techniques work throughout the whole body but for focus I'll be keeping our attention on the face here.
Step 1 will be adding skin pores! This is pretty easy but be wary if you have any form of Trypophobia. Good reference is key, so make sure to get some high quality, high resolution images. Size, Depth and Variation are the only things to keep an eye on. Working with something like ZBrush layers is a great way to have a lot of control over the depth of the Skin Pores. I always over sculpt so that I can use my layers to reduce it a little bit. Keeping our attention on the face, we can see here:
Our skin pores exist! They're there. It still looks off though. Something isn't right, and that's because our skin lacks DIRECTION. What do I mean by this? Our skin is very squishy, and our body moves a lot. Skin Direction is essentially the micro-creases in our skin caused by simply moving. It adds flow and breaks up all the holes in the skin. Skin direction, these micro-creases flow perpendicular to how our skin moves. After looking across some reference, I made this little guide for the face.
All these arrows are how the little micro-creases across the face flow, this is only a general guide because all faces are different. But this is what it would usually look like. When it comes to brush work inside of ZBrush, I used J_FineWrinkles from this, although if you don't have J Hill's Skin Detail's Kit the Dam Standard with Alpha 60 set to Colour Spray will work just fine! If we follow the guide above and add micro-creases in the areas and directions above on a new Zbrush layer we could come up with something like this:
Our skin has little creases and with it: direction! Adjust this layers intensity however you want, the deeper the creases, the older your character will look. These are two pieces of a whole, so after we add our creases it's time to turn on the pores and adjust the intensity of both. Our goal here is to marry them together. There's no tricks here, just make sure you have good reference and a keen eye.
And here it is! A face with some good height detail. After baking we should have some excellent AO, Curvature, and Thickness maps to drive the rest of our texturing process.
Thanks for reading along! Up next is all about creating the Diffuse map.