Realistic 3D Cat Model Groomed In XGen

Massimo Righi has walked us through the process of creating fur for a realistic 3D cat model and discussed the tools he used to make a cat look lifelike.

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Hi everyone, my name is Massimo Righi, I'm a native Italian 3D Creature Artist. I team up with my wife Silvia who's helping me as a Key Artist. In the early 90s, we owned a bookstore. While I was selling books, my passion for computer graphics kept growing and growing. In those years the only resources available were art-related magazines so I kept reading as much as I could and began learning 2D and 3D software myself. 

My passion for animals was, and actually is, the core of my learning curve. I always dreamed of recreating the animal kingdom in 3D. So, I began building up my portfolio, and while still owning the shop I got my very first project as a freelancer responding to a post on Craigslist.

At some point in the early 2000s, we decided to sell the bookstore and fully commit to CG so we started producing 3D animal assets to sell on 3D marketplaces. This way we had some passive income while waiting for freelance projects. Luckily, I got noticed very soon and was featured in online and printed magazines such as 3D World Magazine and Digital Art Masters. 

I have to say that although working as a freelancer is not always easy because nothing is certain and you have to manage all by yourself, I've never needed to apply for a permanent job. I'm very happy and satisfied with what I'm doing because I'm totally free to decide my own path.

In more than 20 years we created hundreds (thousands) of models that have been used in commercials, games, and movies. A couple of the latest projects I'm particularly fond of are an episode of "Always Sunny in Philadelphia" where I worked on a CG monkey and two Bayer's Advantix commercials where I recreated the dog’s heads. I'm also grateful for cool collaborations such as the one with Autodesk that is going to use some of my models for the upcoming Maya Campaign.

As the main 3D packages, I use Maya, ZBrush, and Mudbox

The Black Cat Project

The Black Cat project isn't something new. I started modeling cats years ago. The first attempts were made using Shave and a haircut for fur, but then I switched to XGen since Shave was no longer supported by the newer Maya releases (I've attached a few cat renders I made in the years). As an animal lover, I obviously love cats and black cats have something intriguing and fascinating.

Speaking of the "black cat-walk cycle", after I finished the full model I gave it to Sanjeev Dhama, the rigger I used to work with. As always, he did a really great job with it, so I started to play with the rig and I created a few poses and renders. Upon one of the latest posts on LinkedIn, I got a message from Vaibhav Trivedi, an animator at DNEG, who kidly offered me to animate my models. I was happy to accept the collaboration and sent him the cat rig. Once received the awesome animated file, I set up everything and rendered it.

The Workflow Behind The Process

The first step was collecting the reference material which consisted of photos and videos. Also, I searched for anatomy references, even if I had an animal anatomy book that was always handy.

I did the base model in Maya and sculpted it in ZBrush. Later, I extracted the Displacement and Normal Maps. I created the UVs in Maya right after modeling, so I did not need to recolonize the geometry later. 

My wife, Silvia, often takes care of the first layer of sculpting and the rough textures, so I can start focusing on the grooming. 

My XGen workflow starts with manually creating and placing the XGen curves for each fur description. I usually create three to six descriptions: one for the body, another one or two to use as "fill", whiskers, eyebrows, and eyelashes. Then I start applying the modifiers. I immediately assign the draft texture so I can see the result in real-time with Arnold, going back and forth between Maya and Mudbox, which I use to tweak the textures according to the grooming while testing the fur shader as well. 

I start with creating Density, Width, and Cut Maps. I usually assign three or four layers of clumps, two to three layers of Noise, and a cut modifier. I like to work with Maps, so I paint Maps for each modifier and tweak them with basic custom expressions just to randomize, or to give a range of parameters to the actual values. I paint Maps directly in Maya and, if necessary, adjust them in Mudbox. When I'm happy with how the fur looks, I create a bake modifier for each fur description to speed up testing the rendering. All the process is done using a pretty basic lighting setup: a skydome with an HDR image and two to three areal lights. I like to change the HDR images to test how the fur shaders react to higher or lower dynamic ranges, so I can start feeling the mood of the final render.

The last step is to fine-tune the fur shader and skydome settings. I use Maya Physical Hair, Arnold aiStandardHair with aiColorCorrect nodes, and Ramp Maps to give the fur more dynamism in terms of color variations.

For the final render, I use an Arnold Camera (AA) value of 8 or 10 paying particular attention to the transparency depth that will also affect the fur look. The main challenge is to reproduce the likeness but also, in the case of cats, to capture the cuteness or mood, sometimes with just subtle but effective facial expressions.

Final Words

To get a good final output you need to learn how to make good use of your eyes, understand how to observe, and develop attention to detail. You never stop learning and when I look back to my previous works I always see things to improve, even the recent ones!

It's very important to me to take breaks and relax my eyes from time to time. Sometimes I also put a character on hold for a few days, so that I can get back to that later with fresh eyes.

From beginners to advanced I'd like to suggest a Facebook group for groomers, CG Grooming Artist, it's a great resource of fur-related stuff where you can post your works and get comments and tips from seniors and fellow artists

Massimo Righi, 3D Creature Artist

Interview conducted by Theodore McKenzie

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