Combining Skin and Hard-Surface Workflow in ZBrush and Substance Tools

Introduction

Hi, my name is Masao Hieno. I'm currently an Environment Artist and work on pre-rendering cinematic trailers for various game titlesю

I originally studied painting at the Tokyo University of the Arts. Around that time, a friend of mine started working at Polyphony Digital as a 3D CG artist.  Their work and the quality of video game graphics made me interested in the world of 3D CG. And I also applied for the job of part-time 3D CG artist assistant and fortunately started working there.

After working on the Gran Turismo series, I moved to my current company as an Environment Artist.

About the CGMA Course

The main reason I decided to take CGMA was that I can receive interactive guidance such as individual feedback and Q & A from an instructor every week.

I was also happy because I was inspired by the works of other students who attended at the same time. Another reason is that the work of Ben Erdt who was in charge of the video tutorial for this course was very attractive for me.

I wanted to improve my skills of design, sculpting in ZBrush, and hard-surface modeling. Moreover, I also wanted to create high-quality work for my portfolio.

After considering my aim and CGMA style, I decided to take the course because I thought it matched my aim.

Working with References

In this course, first, students choose one of the multiple concepts to create hard-surface armors and characters.

After choosing the concept, I analyzed it and collected various photo references. I think it's very important to refer to real-life references in order to create a high quality and convincing model.

Whenever I am unsure about a final image of my work during the production process, I always gather necessary photos from the Internet and use them as a reference.

Also, the concept art I chose was from the front. So I had to design the hard surface armor on the back and details. At that time, I designed it with reference to the internal structure of various machines. The inner panel of printers and an engine of the aircraft were very good inspirations.

Modeling

First, I roughly sculpted the creature's body on ZBrush. I cut out the armors from the base body along with the shape of it. I mainly used Mask Curve, Clip Curve, ClayTube, and Move brush to create large shapes, and also use hPolish to make shapes smooth while maintaining a large shape of armors. I also added small holes and lines using those brushes.

After creating the body, clothes, and armor shapes, I made some poses on Maya. I checked whether the hard-surface armors don't interfere with each other, and there was enough space for the arms and legs to move. When I found a problem of interference, I fixed the shapes of the armor on ZBrush. After that, I made the armors smooth and added details more on ZBrush.

I created alphas from the models created on Maya and used them to create brushes for hard-surface details. I was able to add mechanical details easily by using these brushes.

Then, I brought the armors back to Maya for retopology and refining shapes of the hard surface armors. Mechanisms around the wings were modeled on Maya.

After finishing retopology and refining shapes, I brought those models back into ZBrush. And I added damages of small scratches and dents.

For sculpting surface damage, I created alphas and used them to add detail. I created a height map using BitMap2Material from photos of metal scratches. In the end, those are about 400 parts including the body, suit, armor, etc.

Regarding anatomy, I referred to the human body and the legs of birds. The book "Anatomy for Sculptors" has greatly helped me understand anatomy. It was a very easy-to-understand and useful book for me.

Also, I was greatly helped understand anatomy by the advice of Laura Gallagher who was the instructor when I took the course.

I had some feedback about anatomy through a recorded video by Laura so that I was able to fix some unnatural parts of the base body in the early stage of sculpting.

Texturing

Regarding texturing, I had to texture many parts, so I decided to use Substance Designer. I can change the geometry and UV after texturing by procedural texturing using SD. First, I unfolded UV on Maya and placed them for each UDIM tiles.

Then, I textured a part of the hard surface and applied procedural texturing to other parts. I used textures of Substance Source and simple single color textures as base.

I layered them using baked maps from geometry and output maps from ZBrush. Also, I used SD's noise, scratch, Mask Generator, and so on.

Each texture is very simple. I think I can create a complex and convincing texture even with simple materials by layering using Generators with some maps from SD and ZBrush.

In addition, I used the vertex color on Maya to create masks for each material of metal, plastic, rubber, and so on. I applied each texture for each part using those masks.

Moreover, I used Polypaint to paint the rough area where I wanted to apply oil stains and used it on SD as a mask.

Regarding dirt and rust on metal, I used a combination of Ground Dirt node and Dirt node on SD. The closer the parts are to the ground, the more strongly the parts have dirt and rust.

I also used SP to create masks of small stickers. Basically, most of the hard surface armors were textured on SD.

Skin Workflow

As for the creature, I took it to Substance Painter and projected the displacement maps that I purchased at Texturing XYZ  after finishing sculpturing a base body.

Then, the displacement maps from SP were combined with the displacement maps from ZBrush in Maya. I chose this method because I thought that this method was faster than modeling all the fine skin details on ZBrush. This workflow is based on the tutorial in Texturing XYZ.

I also added sculpting considering the projected displacement by using Layers of ZBrush. Regarding texturing, first, I painted the base color of the skin on ZBrush.

Then, I added details to skin color textures on SD by using occlusion and curvature from projected displacement maps and color maps from Polypaint.

I used the Gradient Map node and some maps that I blended the output maps from SP and ZBrush as an input of the node. I was able to add complex colors according to the geometry to the diffuse map by picking a color in the Gradient node from the photo.

I also modeled nails and teeth on ZBrush. After creating the shape of the base, I added details using alphas of scratches and dents. I also used SD and textured it in the same way.

Working on the Armor

Designing hard surface armor was one of the big challenges for me. It was a great learning for me to analyze the design, shape, and details depicted in the concept art and extend it to the back armor which is not depicted in the art.

A particularly useful part of the design process was a balance of shape and detail. I occasionally added too much detail to models in a modeling process. I learned that placing the right amount of detail and paying attention to negative space and balance is important for creating a high-quality model.

From a technical point of view, creating hard-surface armor on ZBrush was also one of my challenges. I usually use ZBrush for rocks, ground, destroyed buildings, etc. However, I have not used it for hard surface modeling until this course. So the process of shaping and adding hard surface detail while maintaining a smooth shape was a very useful experience.

I learned so much from each process that they were helpful.

Lighting 

First, I modeled and placed a roof and window grids and placed a spotlight on it. The models were very simple because they were blurred by defocus.

In addition, I put some Arealights as fill and rim lights. Moreover, I  added aiVolumeScattering to this scene to create dramatic lighting. This allowed me to create a very atmospheric God Rays. I referred to this helpful tutorial by Arvid Schneider.

The rest of the lighting for images of the creature standing on the ground was rendered using IBL with an HDRI map of a sunny day. Finally, I tweaked the lighting a little bit and added vignette and DOF.

The part I wanted to highlight most is the hard surface armor. I was particular about the details around the shoulders and chest, and the design of backside armors.

Biggest Challenges

As I mentioned above, designing hard-surface armor was one of the biggest challenges.

The process from concept sculpting with ZBrush to creating the final details was a great learning experience for improving my design and modeling skills.

Another challenge for me was creating this model as a production level. So I was also conscious of keeping models clean. Creatures, weapons, and hard-surface armor are made with all quads without any geometry errors.

The course at CGMA taught me the entire modeling process including concept art analysis, sculpting hard surface armor and creatures with ZBrush, checking the range of motion, and retopology. 

The instructor, who was Laura, gave me accurate feedback on anatomy and the balance of shapes and details. Her feedback was very helpful because there were many points that I wasn't aware of and familiar with. I was able to understand those points accurately and deepen my knowledge from the feedback of individual recorded videos each week.

I enjoyed designing very much from this work. I would like to improve my 3D skills and deepen my knowledge of design more through my personal works in the future.

Finally, I am very grateful to CGMA for providing a wonderful course. I am also grateful to 80 LEVEL for interviewing me.

Masao Hieno, Environment Artist

Interview conducted by Ellie Harisova