Animal Anatomy Study in Zbrush

Maria Panfilova talked about her new project, where she re-created lion anatomy in ZBrush. You can also purchase this model on Gumroad.

Reference

When I found this book – Wilhelm Ellenberger, «An Atlas of Animal Anatomy» – and saw amazing detailed illustrations with their own aesthetics, I wanted to sculpt at least the head, but it turned out I made the whole lion.

I think making an ecorche is a really rewarding learning practice. While you solve this anatomy puzzle, all relationships between elements become one mental image.

I made a lot of these studies but they were mostly unfinished. The first time I completed an ecorche was thanks to Ryan Kingslien`s tutorial – Anatomy 2.0. It helped me a lot.

Besides, any finished ecorche is a very useful tool when you make your sculpts. You can find a human model in ‘tools’ that comes with default ZBrush installation.

Workflow

I didn’t model everything myself. I used some scanned data at the start: the bone scans of a lion skull, a dog pelvis, and vertebrae. I found them on Sketchfab.

3D Dog Bone Project: C7 vertebra by nzfauna on Sketchfab

From the start, I tried to keep all muscles in their own named subtools. That means you should use Transpose master a lot when you want to work with a whole shape or import it to Maya from transpose master and tweak there.

To keep accurate proportions, I constantly checked my model with the reference image plane in Maya.

I combined elements into larger groups. The new feature of ZBrush 4r8 – grouping subtools was very helpful. 

Check out this little video from Kashif Riley to learn more about this feature.

It is important to name everything right when you have so much subtools. Then you can easily find everything by pressing “N” and using the first letter of the subtool.

Hand-made topology would take much longer – so I used Zremesher with some hand editing.

I made auto-mapping with UV master combined with hand editing and packed UVs into UDIMs. UDIM workflow saves time later. For my pipeline it fits well (ZBrush, Substance Painter, Maya, Redshift). But I know there can be some problems with UDIMs in other software.

Creating muscles in 3D

It is very important to build an accurate skeleton before you move to muscles. It is necessary to link the muscle position with some stable point. If the skeleton has some proportional problems or mistakes it will affect the rest of the model.  

Then you basically need to work with each individual muscle.  You should know muscle’s origination, insertion, how thick it is, how it is placed towards the skeleton and neighboring muscles. Once you figure out all that, the rest will be easy.

A book that helped me a lot with that is Animal Anatomy for Artists – The Elements of Form by Eliot Goldfinger. It has an image of each individual muscle and a description.

One of the closest relatives of cats are dogs. They are both carnivores with binocular vision, they both have to run fast to catch their prey. That’s why you can use dog references as well. But keep in mind the differences.

One of the common mistakes is to make muscles too bulgy and too separated from each other. In fact, they are not that round and thick. If you check dissection videos you will see how close the muscles stick to each other and form the solid shape. I can compare it with orange slices which are flat where they stick to each other but together they form a solid round shape.

Superficial muscles often show the inner structures under them, especially in places where the muscle narrows down into fascia. Zproject brush helps with that.

For the fibre’s direction, I made a brush with alpha and used it along with the ‘smooth directional’ brush. An alpha gives many lines that look random. It should be mainly black with thin white fibres. You can take a texture like marble and invert its colors for a similar effect.

Sculpting blood vessels

The veins are a very variable structure but there are some big veins that are relatively constant, and they also have their own names. In anatomy books you can find some maps of veins. You can easily add them with curve-tubes, sometimes duplicate them and use Zproject brush to stick them to the surface in a better way.

Texturing in Substance Painter

Texturing is very important. With materials, I could type the names of the elements on the surface, indicate materials – bones, muscles, ligaments, glands, fur, veins with different colors. Plus it just looks more artistic with the texture.

It is important to have enough texture resolution, so details from the sculpt don’t get lost and small bump noise reveals even more of them.

In my case, it was 13 sets of 4k textures.

It all was done in Substance Painter (the SP scene is included in the Gumroad package).

For the text, Substance Painter has ‘font’ alphas. You type the word in the brush menu and use it as a stamp.

I made transparency maps for some ligament and fascia so the inner elements could be shown beneath them. 

Highlighting the muscles

For the main images, I wanted the lighting to be bright and luminous (as in a book illustration). In the images with the black background, the light can be more dramatic and outlined with shadows. I prefer to light the mesh from the top, side or sometimes from the back, but never from the front because the surface will look too flat.

I used Redshift for rendering with GeForce 1080Ti graphic card. It’s a really smooth and nice experience. The final image, 4500 pixel wide, took about 11 minutes.

With textured models, I prefer to use white light and if I want some color tint on it, I add some color adjustment in Photoshop. In this case it was “color lookup” -> “crisp winter” adjustment.

The color and light editing can always be done in Photoshop. You should only make color masks for your objects. It’s better to render in 32 bit exr then you will have a larger range for changes. I also add sharpness in Photoshop in the end and sometimes chromatic aberrations.

The Challenges

The hardest thing was to analyze the information from the book: what muscles go where and how they interact with each other. It was very confusing sometimes.

There are not so many sources for animal anatomy where you can double-check the information. My goal was to deal with that difficulty and to improve this situation.

Another challenge is time and keeping patience. But when you think you are making not just another portfolio image, but some work that will be a product and people will use it, it helps you to keep on.

Maria Panfilova, Character 3D Artist

Interview conducted by Kirill Tokarev