Creating a Bat-Like Creature in ZBrush & Marmoset Toolbag

Introduction

Hello, my name is Mike and I am a Character Artist at Amazon Games. At the time of the course I was working as a Outsource Integration Artist. I signed up for the Creature Course to improve my skills as an artist and make the transition to becoming a 3D character artist. I had taken a Character Artist course with Marcin at Vertex School previously (more on that in the next section), so I already knew the quality of the course and the instructor based on how much the first course helped me develop.

Enrolling at Vertex School is very easy. The course syllabus is listed for each course on the website. For the first course, I found the correct course then applied. Shortly thereafter I had a quick interview with the Vertex team to make sure my ability fit the course's educational level. After that you get pulled into the community where you get frequent updates and can post for feedback and review. Those updates are how I found out about the creature course.

Since I was already a graduate of Vertex, I had to apply once the course was launched, no interview this time around. To recap, I originally took the creature course with Marcin to transition to a character artist position and as you can see by my introduction, this course/creature did in fact improve my portfolio and helped me become a Character Artist.

Course Organization

The Creature Course was a 10-week course that convened on Saturdays for video lectures/conferences. The course was a mixture of Marcin showcasing a detailed walkthrough of creating a creature from beginning to end as well as critique and Q & A sessions. Each student would create their own creature and stay on the curriculum's development path with Marcin and his character. There was the option to submit progress between classes on the class forum. This was an opportunity to get additional feedback from Marcin as well as the other artists enrolled in the course. The course’s weekend format was extremely convenient, as I have a full-time job in the industry and freelance as well. In my opinion, the constructive critique sessions with Marcin were the highlight of the course. He would offer multiple points of view and suggest possible changes. He ensured that creative control of the creature was still in the student’s hand, while simultaneously suggesting multiple adjustments to enhance the student’s vision and direction. 

The Bat Creature Project

I initially didn't have a firm decision on what direction I wanted to go. I chose three different types of creatures: a bat-type creature, a chimera-type creature, and a troll/orc-type creature. I pulled base references for each and did some exploratory sculpting. This was mainly shape and form exploration. The bat-type creature appealed to me the most, so I began collecting additional reference and began planning out the process. 

Reference

I broke my initial reference into three main categories. My reference list expanded and shrank depending on what I was working on and what phase of development I was in. The below image is my initial reference before I started sculpting. 

• Red: First, I wanted to research existing takes on bat creatures. I also needed to better understand different species of bats, bat anatomy, and creatures that inspired me like the star-nosed mole. I also used Wyverns as a reference for the arm/wing similarities. The more references the better.
• Green: I needed realistic human anatomy. I always have books on my computer as well. Anatomy for 3D Artists and Anatomy for Sculptors are a few of my go-to books. My realistic anatomy reference ranged from bodybuilders for muscle placement/striations to historical images to see how skin interacts with bone and muscle in a state of starvation.
• Blue: I always have exaggerated examples as well. These exaggerated examples showcase how light plays with muscle, bone, and skin. 

Approach to Bat Creature

The anatomy of the bat creature was the focal point of this project. I knew that if I wanted this to be a believable creature that its anatomy would have to be front and center. For me, to create a believable creature, I needed to create a backstory. I had to design a world and environment that this creature would inhabit. I needed to know what this creature would eat, how it hunted, and how it would attack. These decisions led to the anatomical designs and the reference selected. Once I gave the creature all of the world-building information, I was able to make creative decisions regarding its anatomy. Since the creature lived and hunted in an underground labyrinth of caves, it would be very thin because the food was scarce. The creature would have evolved to lose its eyesight and eventually its eyes completely. It would have large ears, and a motion-sensitive nose because hunting in the dark would require these enhanced senses.

Micro Skin Details

The creature’s skin and surface details were created using both ZBrush and Marmoset Toolbag 4. In ZBrush, I took a 5-step process to create the micro skin details. Note: I would jump back and forth throughout this process as necessary to achieve the right look. 

Step 1: Primary and Secondary Shapes

I ensured that muscle mass, muscle definition, skin folds, and veins existed prior to jumping into surface detail. This is super important–having the underlying anatomy and skin in place will do a lot of heavy lifting when it comes to the skin detailing. 

Step 2: Skin Patterning

Marcin demonstrated this technique for the class and I absolutely love it. I started with the Standard brush, selected spray in the stroke menu, then selected an alpha (in this case it’s alpha 60). Lower the intensity to 2-10 and adjust the brush size to your liking. Create a layer, hold alt (sub) and do cyclical strokes with your stylus. The goal here is not to create skin, just create noise so your mind can start to see skin shapes. I related this to looking at clouds, your imagination will give shape and form to the noise.

Step 3: Skin Reference and Alphas

I researched what kind of skin I wanted on which portions of the body. For example, I wanted harder, cracked, leathery skin on the back and chest and supple leathery skin for the wings. I took hi-res leathery skin references and turned them into circular alphas that become more transparent towards the edges. On a separate layer, I used the standard brush, selected drag rec in the stroke menu, applied the desired alpha, and adjusted the alpha’s Mid Value to remove large clay movement and only keep the fine detail. 

Step 4: Emphasizing Height and Depth

Marcin demonstrated this and he also put a lot of emphasis on this step. After I applied the surface detail, I enhanced the skin and made it more three-dimensional (in a separate layer, of course). This is extremely time-consuming but is completely worth it. In this phase, I mainly used dam standard, standard, move, and clay buildup. I would look at the skin at a medium distance and use the dam standard to carve deeper cuts into the patterns from steps 2 and 3 into the leathery skin. I would also move muscles around and use Clay Buildup to develop height where necessary. I enhanced skin folds and wrinkles, muscle striations, veins, skin tension areas, etc. This is what makes the character’s skin believable at a game distance. These “more” three-dimensional skin attributes can be read at a mid-distance which gives a better internal shape structure when compared to just surface noise alone. 

Step 5: Skin Uniqueness

I always do one final adjustment when I think I am done with skin texturing. I selected the standard brush and chose spray in the stroke menu and turned off the alpha. I set the stroke placement to 1. I adjusted the size of the brush (from big to small) and painted over the entire model. This creates uneven and lumpy skin. This can be procedurally done in the noise menu. However, I always like to do this part by hand. I sculpted layers with higher intensity, then brought down the intensity of the overall layer to my liking. My goal is for this to break up the skin's surface without affecting the skin texture. I like to think of it as subtle skin waves.  

Marmoset Toolbag 4 Process

• Step 1: I applied an already existing skin material that had some height information. This gave me a base to work from.
• Step 2: I hand-painted more height details to emphasize specific parts (like the veins).
• Step 3: I used a Curvature mask on a fill layer to increase the depth and color of the cavities.
• Step 4: I used a detail Normal Map to add variation to the skin and create a more interesting interaction with the light. This step was done after the texturing.

Retopology

To prepare this model for retopology, I separated the bat creature into body, claws, and teeth in ZBrush. From here I duplicated and ZRemeshed the claws and teeth. Then I subdivided and projected the information from the pre-ZRemeshed model to the ZRemeshed model. This gave me a workable topology for the claws and teeth. For the body, I decimated the model and exported it to Maya for retopology. I hand retopologized the model using quad draw. My intent was to keep the creature under 50K polygons. The model ended up being 46912. I wanted the primary shapes and silhouettes captured in the low poly geometry. My intent was to have the Normal Map handle surface-level detail, not large-scale height and depth information. 

Wings in general add a lot of geometry that coalesce into very dense areas, like the hands. For these areas, I try to have EdgeLoops that run around the webbing between the fingers. This allows the topology to loop in the webbing without running into the hand. In addition, I still had to terminate EdgeLoops on the top of the hand to remove extraneous EdgeLoops because the wings are triangle-shaped.

Another area that had to have extensive EdgeLoop termination was the jowl detail: the face and connective tissue between the jaws did not supply the necessary topology to get a solid bake in the jowl detail. This process consisted of a lot of trial and error. I would adjust the topology density then bake, review the bake quality, and do it again until all bake details were captured correctly.

For UVing the creature, I cut along major anatomical shapes. I made sure that the texel density was even on the body. I tried to keep the UV sections vertical or horizontal. I was not too concerned with seams. Most modern engines and texturing softwares are good at blending textures over seams. That stated, I always double-check my assets in multiple lighting environments and engines to ensure seams are not visible. If the seams are visible, I remap the UVs with the seams in hidden areas not regularly seen by the camera. 

Texturing

This was the first time I had textured a full character in Marmoset Toolbag 4’s texturing suite so there was a lot of trial and error, as well as experimentation. Every single step and example below was done in a non-destructive way, which means I used fill layers with masks. I also used Marmoset’s ray tracing feature which is a mixture of real-time rendering and ray-traced rendering. This means after I made an adjustment I had to wait a couple of seconds for the render to complete to review the final results. On a separate note, it was extremely nice to texture in the same software I was rendering in. My process for this creature was as follows:

Step 1: Base Layers

I applied a base color fill layer, base skin material, a roughness layer, and a Cavity Map to the material, as well as a Volumetric Scattering layer. I was not worried about subtle or even large-scale color changes. This was about the skin reading as skin. At that moment, I was not worried about the intensity of the Volumetric Scattering on the wings or ears, that would come later. 

Step 2: Gradients

Marcin suggested that I start with gradients so I applied a number of gradients to the creature. Starting with a top-down and a bottom-up. This made the creature lighter up top and darker down low. Then, I added sectional gradients to the creature. This would include varying colors to represent areas where blood flow would be closer to the surface (wings, arms, head, ears, etc.). Then I did internal top-down gradients for individual body parts(wings, the body, the ears, etc.). This would give each component of the creature a unique feel. 

Step 3: Procedural Skin Breakup

For this step, I used Marmoset’s equivalent to Substance generators. I used various noise and dirt Maps of varying scale (large to small) and color (light to dark) to create a base-level skin breakup. I would also use curvature (small to large) with varying intensity and blending types to enhance the recessed skin and pore detail. The goal here is not to have a unique skin breakup but a general skin breakup. 

Step 4: Major Color Variation (hand-painted)

Here, I hand-painted masks that handled color and Volumetric Scattering. I cranked the material scattering from 1-2, which I used for human skin, to 15, which creates the intense scattering in the wings. I used masks to bring the non-translucent skin back to normal scattering levels. This is also where I added the yellow and the lighter, warmer colors to the wings and ears. I used Overlay or Soft Light as the Blending mode and duplicated the layer for intensity. This allowed the procedural skin break-up to show through slightly. 

Step 5: Minor Color Variation (hand-painted)

For this step, I would repeat the previous step but with a focus on hand-painted smaller areas. The difference between the cheeks and jaw or scapula and back for instance. As an example, I would paint warmer colors starting from yellow, to orange, to red (to build up color) on areas where the skin is stretched tightly over bone like the scapula, the collar bone, elbows, iliac crest, etc., while painting cooler purples on the large faces of the body. This is also where I added analogous colors for the sensitive areas. Since the creature has a lot of purple, I used pink and lighter purples to handle wings, nose, and mouth. This keeps the color palette similar. My goal was to have my primary and secondary colors be complementary while having some analogous colors as the tertiary details like the nose, ears, wings, etc. 

Step 6: Additional Skin Detail (hand-painted)

This is where I did a deep dive into hand-painting. This is the fine detail and unique skin surfacing that the procedural generators cannot give you. I added varying levels of blur, intensity, and blending modes to achieve what I was looking for. I also painted subtle blurred darkness between primary muscle groups to help differentiate the muscles. I added the color variation for the scarring and damage to the skin. Finally, I would make sure to blend all of these areas together. Everything should have a color transition between them. For example, the bone color of the claw should not run directly into the skin of the finger.

Step 7: Roughness

For the roughness, I enhanced the Cavity Map with a curvature layer to make the recessed portions of the skin less shiny. From there I added a couple of subtle noise generators to add variation to the roughness on the skin. Afterward, I applied some hand-painted roughness with a dirt brush to make sure specific elements behave correctly in the light. While this process is not realistic, it looks great on some characters.

Step 8: Dirt

I added both procedurally generated dirt layers as well as hand-painted dirt layers. This is always my last step. I want the character’s colors and roughness to hold up regardless of the environmental impact.

Bonus: Marcin suggested this in my first course with him. I took the green channel of the Normal Map and copied it. I brought it into Marmoset and set it as a color fill layer. I turned the blend mode to overlay and reduced its opacity to 10-20%. This gave a bit of baked lighting information and self shadows the creature. This is extremely subtle but makes the creature pop!

Final Presentation

Posing

I used the transpose master in ZBrush to pose the creature. Marcin emphasized that the pose of this creature was essential. A lot of effort was put into the creature's anatomical silhouette so it made sense that its pose created a unique silhouette as well. 

Volumetric Scattering

I initially used SubSurface Scattering; however, Marcin suggested that I use Volumetric Scattering since I was using Marmoset’s new ray-traced lighting and reflection enhancement. I cranked the material Volumetric Scattering to 15 to allow light to shine through the thin parts of the creature. I used masks to bring the thicker skin areas and veins back to believable levels.

Marmoset Post Production

The biggest factor here is that I was using ray-tracing. This means I didn’t adjust the AO and didn't have to hand paint additional AO as much as I would have in real-time render. I used Hejl for tone mapping, a contrast value of 1.01, and zero grain. 

Dust

For the dust, I created small polygon planes and randomly placed them around the creature in Maya. I duplicated the group and rotated. I used a script to randomly select a percentage of the planes and adjusted the scales. I used a dust image and created a normal map for it in Photoshop. I then combined the dust and brought it into Marmoset. I added the color map and normal map. I adjusted the transparency accordingly. This effect can be hand-painted in Photoshop as well.

Photoshop Post Processing

The smoke and embers were added via a Screen Blend mode and fair use images. I added a subtle streak of light from the top left to the bottom right on the final rendered image. I added a semi-transparent grain and vignette to the image (all of which could have been done in Marmoset’s post-processing stack).

Lighting

I did a custom lighting setup for each camera in the scene. Marcin suggested that I take a dynamic lighting approach that borrows from Baroque lighting. Baroque-inspired lighting was a great choice for this creature, the tenebrism makes for a dynamic and dangerous-looking creature.

Lighting Setup

The lighting setup I used for this creature makes for good renders. However, it is not ideal for in-game lighting as I have light sources at different heights and locations throughout the scene. For ease of digestion, I will classify my lighting groups (in three-point lighting terms) as Main, Fill, and Rim.

Main Lighting

My main lighting group highlights the key features to which I wanted to draw attention. Here, I have a head and sternum light, a body light, and an arm light. My main lights were warmer in color with the exception of the head light which had a slight blue tint so as not to influence the yellow on the collar bone.

Head, Head + Body, Head + Body + Arm:

Fill Lighting

Here, I used cooler colors to highlight the areas not lit by the main group. My lights consisted of rear leg light, secondary face light, wing light, and backlight.

Rear Leg, Rear Leg + Face, Rear Leg + Face + Wing + Back:

Rim Lighting

Here, I placed lights that would backlight or create a rim around the creature. The goal with the rim group is to engage the Volumetric Scattering and light the edge/silhouette of the creature.

SSS, SSS + Back, SSS + Back + Shoulder Blade:

Conclusion

This course definitely had an effect on my workflow. There was not an overarching ‘eureka moment’ that changed the way I worked. Instead, there were small learnings throughout each phase: pointers on tool usage and quick iteration in the blockout phase, tutelage concerning extrapolating base level skin detail from noise, distinct guidance, and experimentation during the dynamic Baroque-Esque lighting setup. All of these small pointers, tricks, and critiques from Marcin culminated in a creature that is the capstone to my portfolio. I have used many of the things Marcin went over in both my personal and professional work.

Marcin as an Instructor

Marcin is a great artist, mentor, and teacher. He would regularly stay after the allotted course time to help students with questions, tutorials, and even sculpt-overs. He was fully engaged and put in extra time and effort throughout every portion of the class. His experience coupled with his ability to clearly and concisely communicate definitely helped elevate my creature to new heights. I would highly suggest that anyone, regardless of experience, check out a class with Marcin at Vertex School. I know that, without a doubt, Vertex School and Marcin Klicki have had a direct impact on my skill level and aided in my journey to become a AAA Character Artist. A journey that was just realized after years of effort and work. 

Mike Moore, 3D Character Artist

Interview conducted by Arti Sergeev