Introduction:
For this project, I focused on creating textures for organic foods, utilizing Substance 3D Designer, Substance 3D Painter, and Unreal Engine. The project involved developing two distinct versions of each object, one representing the fresh state and the other depicting the decayed and rotten state, showcasing the contrast in textures and material properties. The scene was rendered in Unreal Engine, with control over the amount of subsurface scattering (SSS) in different areas of the model. The key of this project was to learn how to control SSS and give organic materials a more realistic appearance.
References:
To start the project, I gathered detailed references for each of the organic foods I was working on. For items like potato, pepper, cheese, and bread, I noticed that mold growth is a prominent characteristic as they decay, with white and green mold spots forming on the surface. While for the meat, specifically the steak and octopus, the flesh darkens over time, shifting to deeper shades of brown and blue. These observations helped guide the texturing process, so that each food type had its own unique decay pattern.​​
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Modelling and UV layout:
I began by sculpting the objects in Zbrush. I focused on capturing the basic shapes without adding too much detail, because I wanted to create the details with the texture maps later. After that I exported the models into Maya and laid out the UVs for each object. I also adjusted and changed the UVs a couple of times later during the whole project to make the textures seamless in front of the camera.
Creating base materials in Substance 3D Designer:
First, I started by creating the base material of each object in their fresh stage using Substance 3D Designer.
I tend to start by creating the normal map, which serves as the foundation of the surface details, and then create the other maps using the masks that I created for the normal map, and then tweak the details back and forth. For objects like the cheese and the toast, where they have more prominent dents, I darkened the colors around those areas to further create the illusion of depth, emphasizing the recessed areas. When working on objects like steak and octopus, I focused on making more color variations to give them a more realistic look. Steaks have different shades of red and pink, with layers of fat in between, while octopus have different variations of brown, purple and pink. These are all elements that need to be considered while creating these textures to contribute to the overall organic feeling.
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Substance 3D Painter:
After exporting the base materials into Substance 3D Painter, I began adding some layers accordingly for the textures to better match the characteristics of each object.
For the steak, I added height variations for the surface to make it more uneven, then added the SSS map, where it will get higher subsurface scattering on the edges due to the thinness on those areas. On the potato, I added more color variations and dust to give it a more realistic feeling. For the octopus, its flesh varies across different areas, including the bottom part and the suckers. I used masks to isolate these regions and adjusted their color, roughness, and SSS levels to create the necessary contrast between them. The same process goes for the other objects, I adjusted color variations, as well as roughness and SSS values based on their baked maps. I used curvature maps to target the edges, where I increased the SSS values because as the mesh gets thinner on the edges, more light would be scattered through those areas.
Afterwards, I added a new folder which will contain the decayed version of every object.
I began the texturing process by focusing on the molded parts. From the references, I can see that the molds typically appear as white spots, with green mold growing inside the white areas. So I built up my layers to replicated this. I first created the white mold spots on the surface of the objects. Then, I duplicated the layer, changing its color to green, and adjusted the balance to ensure that the green mold stayed contained within the white areas. This layering technique helped create a more natural, realistic mold effect.
Looking at the references, I noticed that mold growth was more concentrated on the top surface, so I applied a gradient of white mold that intensified from the top to the bottom.
When working on the steak, I had to approach it differently, as meat does not typically form visible mold but instead darkens as it spoils. Referring to my references, I introduced dark greenish-blue tones along the sides of the flesh. I also added dark brown spots to the top surface.
To further refine the decayed appearance, I reduced the amount of SSS on the moldy areas. Mold typically lacks the translucency seen in other organic materials, so lowering the SSS helped enhancing the contrast between the fresh and decayed states.
Adjusting SSS in Unreal Engine:
After the textures were done, I exported everything into Unreal Engine. For the wooden table, I used a wooden texture I created for a previous project. I exported an HDRI into the scene to establish realistic lighting and reflections. Then I adjusted the rotation of the HDRI so that the light would come from the back, creating a natural backlighting effect.
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HDRI from Poly Haven. https://polyhaven.com/a/pine_attic
The next step was setting up Subsurface Scattering in Unreal. I adjusted the shading model of the material to “Subsurface” and enabled the two-sided mode of the model. I used a multiply node to blend the scattering map and the object’s SSS color and plugged it into the “Subsurface Color” of the material. Then, I adjusted the opacity values with a constant value to give the scattering amount a better control. Lastly, I added another multiply node to the base colors to adjust them further, compensating for how some colors appeared different under the HDRI lighting in the scene.
Conclusion:
This project was a valuable learning experience that helped me refine my skills in using Substance 3D Designer, Substance 3D Painter, and Unreal Engine. I gained a deeper understanding of subsurface scattering and how to control it in Unreal Engine to create realistic materials. By experimenting with SSS settings, I was able to bring more depth and realism to my textures, this project greatly enhanced my technical abilities and broadened my knowledge of material creation workflows.