UVs
I used the basic tools in Maya for UV layouts, using UDIMs. I wanted maximum resolution for the skin, so I used 7 UDIMs for the body mesh to ensure I could retain resolution from my baked maps. The process was:
- Add a quick planar projection to each mesh to have some starting UVs
- Select border edge loops and use the Cut and Sew tools to define the borders
- Then, unfold the UV shells and scale / orient them to fit in the UDIMs. I used the UV checker image to ensure my texel density was even across the mesh.
- I placed the shells in UDIMs according to which mesh they belonged to, to minimize map count later.
- Once done, I brought the UVed model into Substance 3D Painter just to check it. Substance is very picky about UVs being precise, and I had some micro overlaps that it alerted me to. It was a good way to quickly check the UV integrity before moving back to ZBrush for projection and map baking.
Texturing
After all this setup, I was finally ready for Substance! I watched many Substance 3D Painter videos, and there are a lot of great ones out there. I was intimidated by it at first, but Substance shares a lot of DNA with Photoshop. It was not hard to learn the basics, but much like Photoshop, it’s a deep well of possibility, so it will be a long time before I consider it mastered. I have to credit Cryptic Visionary’s videos for getting me on the right track out of the gate.
The Skin
The great thing about Substance is you can play around a lot. It’s very responsive, and like Photoshop, you work in layers to build up a look. You might lay down a base tone, and then add a red color fill and a black mask, and fade it down to get a nice blend. You continue layering in this fashion, building up color tones from the sub dermal layers of skin up to the top.
For this character, the skin was the most challenging surface, since it is the most visible and detailed. It was my priority to get a basic skin gradient first using fill layers with paint masks, and then explore a poison dart frog type skin.
After the basic color gradients were in place, I added a very small 3D Simplex Noise layer to break up the orange tones with some yellow. I blurred the noise a tiny amount and used it in the height and roughness channels for a very subtle orange (fruit skin) breakup.
The black spots on the head were painted with the dots brush, and I used a High Pass filter to break it up. Then I used some Levels and a Contrast / Luminosity filter to crush the darks into more defined spots. I also used an inverted Curvature mask to paint the spots out of the deeper wrinkles.
I painted a blue Fill layer with some veins and pushed them back as a more subtle red. You can really take this technique very far, but I stopped here. In a future challenge, I’ll attempt human skin, which has much more subtle complexity, but it all comes down to building up and balancing layers.
An important step in this process was to set up my Maya Arnold render file and test the maps. The model will not look the same in Maya — the lighting and rendering conditions differ a lot, so I would often bake my maps and check them in an Arnold render. Then, I’d go back to Substance to tweak and re-export maps. This process was quick and flexible.
