Nicole Jackson shared her experience with CGMA and did a breakdown of sculpted antelope Nyala and Dragon. Software used: ZBrush, Maya, Arnold.
My name is Nicole Jackson and I am a 3D character artist from California. I graduated from CSU Chico with a Bachelor of Science degree in Computer Animation and Game Design. I started taking CGMA classes in order to improve my understanding of anatomy since CSU Chico did not offer an equivalent course. Without a formal understanding anatomy, it was harder to produce realistic creatures. In order to learn these skills, I enrolled in CGMA’s Sculpting Anatomy: From Animal to Creature by Gael Kerchenbaum.
The class was set up into two sections with each part focused on a different project. For the first project, we could choose to work on a carnivore or a herbivore. My first instinct was to do a carnivore, specifically a big cat, because those are some of my favorite animals and I have almost exclusively worked on carnivores in the past. I decided, however, to choose a herbivore in order to push myself out of my comfort zone. To challenge myself, I decided to work on a more exotic animal rather than one where the anatomy reference of the exact species was readily available. In the end, I chose to do an anatomical study of a Lowland Nyala (an antelope native to southern Africa) because of their long limbs and elegant proportions.
The Nyala Project: Reference
Before sculpting our projects, we needed to gather reference material and organize it in reference boards using a program called PureRef. Throughout the project, I collected hundreds of relevant reference images including photographs and anatomical studies of Nyalas and similar species (mainly horses, deer, oxen and other antelope species). I also referenced several anatomy books including Animal Anatomy for Artists by Eliot Goldfinger and Animal Anatomy by W. Ellenberger.
This was how my PureRef reference board looked towards the end of the Nyala project:
We started by finding a profile view of the animal we were studying in a neutral pose. On top of the photograph, we drew a diagram of the skeleton and muscle groups’ location within the body. Each week we created a reference board of the relevant images for whichever part of the body we were sculpting.
Here I drew the skeleton over the top of the reference photo of a Nyala and color coded the bones to compare the bones to a human, a Plantigrade animal (chimp), and a Digitigrade animal (Tiger):
Here the muscles were drawn over the top of the reference image:
Kerchenbaum also taught us about the differences and similarities between carnivores and herbivores and how their anatomy varies based on their needs as a species. For example, herbivores, such as horses, need to be able to run in order to avoid predators and, because of this, they have straight spines that aren’t as flexible to provide stability while running; whereas a carnivore such as a cat has a curved and more flexible spine that allows it to jump and pounce on its prey. Keeping characteristics like these in mind is helpful for creating a realistic and believable creature.
We began working on our project by creating the skeleton, specifically the skull. Starting with a cube in ZBrush, we slowly adjusted the shape to match the references we were working from. I frequently used the move tool and the clay tubes brush to adjust the shape of the skull and Dynamesh to quickly retopologize the mesh as I made large changes. ZBrush is a creative and organic process; instead of worrying about topology, you can focus on sculpting in a way that feels like working with real clay. Because of my background in traditional art and clay, many of the methods of working with clay translate to digital sculpting in ZBrush.
Gael showed us a useful technique for creating holes and carving out sections of the mesh by using the Insert Primitives Brush. Using this method, we were able to quickly make cavities for the eyes and nose and hollow out the interior of the skull. During the process of sculpting the skull, I referenced 3D scans of similar skulls on sketchfab and other 3D model viewing websites. Having the ability to rotate around the reference and view it from any angle is beneficial, because it fills in information gaps that the reference material alone does not provide.
Once the skull was complete, we began blocking out the rest of the skeleton. We used ZSpheres, starting from the base of the skull, to block in the skeleton. Getting the correct proportions of each bone was important because we would be layering the muscles, fat, skin, and fur on top of the skeleton; if the skeleton wasn’t correct then it would cause problems down the line. Each bone was sculpted into the ZSphere base mesh that we created earlier using the same tools used to refine the skull; this caused the bones to be fused together but this was fine for our purposes. We were also careful to include the bony features of the skeleton, such as the bumps and ridges on the bones, because each of these features has a purpose; often indicating the attachment point of a muscle or tendon.
Using the skeleton as the framework, the muscles were added one by one on top of the bones; while always checking my references. We used the insert mesh brush to insert a sphere onto the mesh to start a muscle group and then used the move tool to shape each muscle and shift it into place. Once the placement and general shape of the muscle was correct, we would use Dynamesh to connect it to the rest of the model. Once all the muscles were attached, we used the move tool and clay tubes tool to refine the shape of the muscles. As I refined the muscles, there were times when I could tell that there was something not quite right with the skeleton of the creature. When this happened, I would go back and adjust the skeleton in order to fix the problem.
During this process, it was important that the bones of the creature were not lost. There are areas of the creature that have little, if any, muscle covering the skeleton (such as a portion of the ribcage, the hips, etc), so it is important to keep these areas looking like bone rather than allowing them to fade away into the surrounding muscles.
Skin & Fur
The next step in the process was to add the fat, skin, wrinkles, and fur. I duplicated the current model and filled in the holes between the muscles and carefully softened and blurred the divisions between the muscle groups and removed brush strokes. This gives the illusion of fat on the animal; however, it is important not to completely lose the definition of the muscles beneath the skin. Once the general smoothing and refining of the model was complete, we began adding the wrinkles and skin folds. Wrinkles occur in areas that need additional skin to allow for movement such as joints (elbows, around the neck, etc). While looking at my reference, I carefully added the wrinkles; making sure they were not too even or symmetrical so that they would look natural.
Next, I blocked out where I wanted to place the fur by duplicating my model and pulling the geometry through the original model using the move brush and the snake hook brush. Checking the silhouette often, I continued to refine the fur volumes until I was happy with the general shape. Working in smaller clumps, I made several strokes with the clay tubes brush to show the direction of the fur. The trick was to create the illusion of fur without actually sculpting out each individual strand.
The fur is roughly blocked out:
Model with completed fur:
The project was rendered in Maya using the Arnold renderer. I used ZBrush’s Transpose Master to create a simple pose for my Nyala and added it to a Maya scene with a backdrop. I lit the scene using 3-point lighting and added a few additional lights to illuminate the background and key points of the model. The material I used was meant to look like clay and is an AI Standard Surface material with subsurface scattering enabled to give it a nice glow, especially in thinner areas of the model such as the ears.
The Dragon Project: Using Anatomy of Real Animals to Create Believable Creatures
The next half of the course was focused on a second project: a dragon. What was interesting about this project was that, since they don’t actually exist, we had to use the anatomy of real animals and adapt it to work for the dragon. Not only did we learn how to combine and adapt the anatomy of many different species, but we also learned about the anatomy of birds and bats: specifically the muscles that allow for flight.
While looking for reference material, I came across an interesting dragon concept image from an unknown artist. The dragon itself was stylized but I loved its proportions; it had a long neck and tail, but what really caught my attention was its feet which looked similar to those of a lemur. These became the cornerstone of my dragon concept. The story I created for my dragon was an agile, small to medium sized dragon (around the size of a small cougar) that lived in trees. It would have a semi-prehensile tail and feet meant for climbing trees and gripping branches.
Proceeding with this concept story, I decided to use reference of clouded leopards, leopard, several monitor species (especially Spiny Tailed Monitors), birds, and bats as my main reference material. The actual sculpting process was almost identical to that of the Nyala.
My PureRef reference board with all my reference and inspiration images organized:
Dragon skeleton (without wings):
Dragon before final texturing:
I created a layer in ZBrush with the mouth shut to make sure that the jaw and teeth were shaped correctly to allow the mouth to close:
With the dragon project, we took the sculpting a step further and created high detail scales and skin textures. We used alpha maps created from high detail scans of real animal skins such as a crocodile, a frog, an iguana, and even an ostrich. I also hand sculpted many of the larger scales such as those on the head, belly, the legs, and along the spine. I also added spikes along the dragon’s head and neck.
Once the scales were sculpted, we moved on to Polypainting the model in ZBrush. I added many layers of color and used ZBrush’s automasking features to bring out detail in the model. Kerchenbaum also showed us how putting a lighter, sandy color between the scales can give the illusion of dirt and dust stuck amid the scales. Previously, my instinct was to paint a darker color to add shadow but, by painting a light color instead, the resulting texture was much more realistic.
I pictured my dragon living in a rainforest so I decided to have some fun with the texturing and make it rather colorful. I used many shades of blue for the body with some variations of hue into the greens and purples to give the color more depth. Then, I used a soft ivory color for the dragon’s spikes, belly and the inside of his limbs. I added a streak of black across the dragon’s face and tiger stripes along his back. The first iteration of the legs had tiger stripes as well, but I decided that this was too much pattern so I faded the legs into black instead.
Polypaint in ZBrush:
Once I was finished with the texturing, I created a base mesh with a lower polygon count and baked out all the textures so they could be used to render the dragon in Maya. The base model wasn’t perfect (some of the spikes became too low poly and lost some of their shape) so the final Maya render lost some of the detail in the original ZBrush sculpt. I plan to manually retopologize the dragon in my free time so that I can bake the textures again and hopefully get a cleaner result but I am still happy with the final result for the course.
My experience with Sculpting Anatomy: From Animal to Creature was phenomenal and Gael Kerchenbaum is an amazing teacher. The techniques that he taught us helped me improve my skills as an artist and gave me the tools to create any animal or creature I can imagine. I loved that he not only taught us about animal anatomy but also gave us a few tips about being a professional artist and showed us how to texture and render the model to create a portfolio quality image. I would highly recommend CGMA‘s courses to anyone who wants to improve their skills as a 3D artist.
Nicole Jackson, 3D Artist
Interview conducted by Kirill Tokarev