The Beast: Grooming Workflow in Houdini

Marion Carnazza discussed the production of the beast she worked on during the final project at the 3D school, Creative Seeds, dived into the details of creating a fur in Houdini, and talked about the team's collaboration. 

Introduction

I’m Marion, I’m a thirty-year-old French 3D artist based in Paris. I freshly graduated from Creative Seeds after 3 years of studies. I have worked on very different projects (collective and personal) and for the last 2 years, I have mostly participated in making short films as a look development artist. Now I spend my time on personal projects focusing on what I really want to do.

As a child, I drew a lot, watched all kinds of movies, and have always wanted to make something out of it. Later on, I started to study Urban Planning but I continued to explore various techniques through lessons like oil painting, 2D animation, DTP, and so on. Those lessons kept me more excited than my actual studies so one day I decided to quit to be part of the animation industry. Then I found some 3D schools and chose Creative Seeds. I was sure the mentors there could teach all I needed to know in order to work in the industry just in 3 years because I was already 27. I finished my studies this summer and am currently working as a 3D artist. 

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The Beast: Idea

The students of all departments wanted a scary beast in the graduation movie. I was glad to take care of it because it would allow me to get better acquainted with interesting techniques: clean topology for animation, intricate detail modeling for the mouth, a combination of fine displacement and fur grooming.

The story took place in North America so my part of the work was to propose a large creature to fight the good guy. It had to be strong, aggressive, and agile enough to be fast and be a real problem for our hero.

We wanted this creature to represent death, and naturally, we started to think that maybe it had to be something dead! We looked through North American mythology to find something that would fit with the context and came upon the Wendigo, an anthropomorphic evil spirit seen as the embodiment of greed and excess which has an insatiable appetite for humans. It can be bound with cannibalism which was perfect for our story: a hero who fights human transformation into a deadly beast.

Start of the Work

First of all, I usually get started withdrawing a model sheet to help me with the volumes and proportions of the creature. I used some pictures of gorilla skeletons to get more realistic proportions, which I moved around a bit to create a taller animal with slender limbs and shapes. I also watched a lot of artworks of werewolves to see how other artists have interpreted the anatomy of hybrid creatures with anthropomorphic characteristics.

I modeled the beast directly in Maya and after a lot of exchanges with the rigging department, I had the right topology needed for animation and could deliver the beast to them to allow the project to move forward. So no retopology was necessary here. Then, I went to ZBrush to sculpt the details such as the muscles, the scars, the antlers, and the skull and ended up with my displacement maps.

Fur

For fur, I chose to work with Houdini because with a basic workflow and only a few nodes I can create a lot of iterations in a non-destructive way. The goal here was to have a fluid and light workflow between Maya, Houdini, and GuerillaRender.

First, I imported the Alembic cache of the mesh from Maya. Then I applied the displacement maps done in ZBrush for the groom guides to have the correct position on the final mesh. As we decided to render the film with GuerillaRender, I had to export a groom cache for all the animated scenes where the beast appeared. For this process and the render scenes to be lighter, we decided that I would do the groom guides in Houdini, then export an animation guide cache for the animated scenes to finalize the grooming in GuerillaRender, which handles very well subtle parameters such as density, clump, length, and randomization.

For the guides grooming in Houdini, I had a complete sample scene from one of my mentors and a great masterclass from SideFX in order to set up my pipeline. I then had a clear step-by-step guide and from this point, I followed his workflow, alongside the Houdini 16 and 16.5 Hair & Fur Masterclass video series:

I had 4 descriptions of fur: for the body, the head and the ears, and for the long hair. I started with creating some guides and controlling roughly their distribution with a paint mask to remove the parts without fur like the mouth, the eyes, etc. I used another paint mask node each time to set the length, the direction, and the bend of the guides for the different parts of the body. Thereby, I had a correct and very controllable base to work on and export my guides from, therefore I could go on with the look development in GuerillaRender, with some value tweaking. 
Then I refined those parameters with masks in Mari to have more accurate and meticulous control over the details like the clump variation, the crazy hair, or the color shades. With the decimated version of my sculpt from ZBrush displayed in Mari, I could also paint density masks and add fur-free zones to reveal the scars on the character.

Head

For the head, I mainly used the model sheet I drew, and for the teeth, I used a few pictures as a blueprint and model on top of them to get realistic shapes.

The skull was an important part so I found a 3D scan of a deer skull to match the design of the Wendigo and I used Maya's Quad Draw tool. When I was satisfied with the base mesh, I put aside the scan and started to focus on the sculpt in ZBrush. After a while, we realized that the deer skull looked strange on the beast and made him look like a cow or a pig depending on the angles! So I started the skull over and used a coyote skull as a reference to give him predator-like characteristics and make him more aggressive from every angle.

Collaborating with Other Departments

All the animator's aspirations were formulated during the pre-production, so when I started to work on the design, I had a clear idea of the beast's overall stature and what moves it would have to do in the film. All the decisive exchanges were with the rigging department because I had to deliver a clean topology so it could be rigged correctly. For example, to prevent any pinches on the shoulders and preserve consistent volumes, we preferred to model the arms along the body and not in T-pose like it is usually done in production. Though as the frame right below shows, we didn’t always anticipate every situation!

The tricky part was the fur because naturally, the animation twisted or offset the topology and the fur with it. It was visible on a close-up frame, so I had to change some parameters like the density in GuerillaRender on each problematic scene before rendering.

Here’s the film we made at Creative Seeds as our 3rd-year project:

When I work alone, I simply favor the look of my character or the composition of my picture even if I am always careful about making a clean topology. I can be more destructive and make it work for one shot or picture rather than make it work for a whole film, so I can take decisions faster. Though both workflows are very interesting.

Challenges

In general, providing a design is not easy for me, and it was a very important step because if the beast would be inconvincible, the climax would fail. Besides, I started working on the design on the first day of production, so I was already late at the beginning of the project.

The lesson I have learned from it was to always ask for help when you have doubts, share your WIPs as often as you can, and take advice from artists you trust the eye, without forgetting the project necessities. As I was working on something out of my comfort zone, I learned to try and stay focused even when at times it was difficult. I received some great help from great artists, mostly from my mentor and colleagues who were always available when I needed technical help or subtle artistic directions.

As for now, what I wish is to go on working on personal projects to keep experimenting with new techniques, build up my artistic strengths, and collaborate with artists who inspire me. 

Links

Marion Carnazza, 3D Artist

Interview conducted by Ellie Harisova

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