3D Modeling in Animation: Definition, Process & Challenges

Over the past five years, virtually all major movies have relied heavily on 3D modeling, using it to attach characters to virtual sets and create captivating special effects. In modern animation, 3D modeling is an essential component. But have you ever wondered what modeling really is and how it works? In this article, we'll answer these questions and more, taking a closer look at the process, techniques, and tools behind 3D modeling.

What’s Modeling

Modeling is the process of creating 3D models of characters, environments, and props.

3D models are often divided into two main categories:

• Manufactured (hard surface modeling) - Hard surface modeling includes manufactured objects that are mostly static and won’t change much during a scene: background mountains, vehicles, buildings, tools, etc.
• Organic (organic modeling) - Organic modeling requires advanced modeling techniques because of the complexity of the objects at hand: characters with many moving parts, animals, flowing rivers, etc.

Studios can rely on additional categories to subdivide the work and make the whole process smoother. The main benefit of using such distinction is to pick the right modeling technique.

Why 3D Modeling

3D modeling is at the core of modern animation pipelines, bringing three main benefits to creative studios:

• More efficiency - Modeling artists manage complex objects and scenes in a digital environment: animators can quickly make changes to the model without having to start over from scratch, and the resulting speed increase helps deliver high-quality animations in a shorter amount of time.
• Realistic animations - 3D modeling is crucial to create realistic animations―we live in a 3D world, after all. Accurate models help animators achieve levels of realism that would be expensive and difficult (sometimes impossible) to achieve through more traditional animation techniques.
• Greater creative control - 3D models also give animators greater control to create unique and visually stunning animations: you can easily create variations in minutes instead of days, including different lighting and textures to enhance the overall look and feel of the animation.

3D modeling kickstarted a whole new wave of animation projects compared to the 2D drawing era.

Who Is Involved

Modeling artists create 3D models based on references like photos or concept illustrations provided by the art department. They are often specialized in organic or hard-surface modeling and collaborate closely with other 3D departments to comply with technical requirements.

Organic modelers work mainly with the visual development, rigging, look development, simulation, and animation departments to bring characters to life.

Hard-surface modelers collaborate more with the visual development, layout, and look development departments to create immersive worlds.

The 3D Modeling Process

Modeling is one of the first steps in the animation pipeline: characters and settings need to be completed before they can be rigged and animated. But modeling also spans various stages of pre-production, production, and post-production in an iterative loop, including modeling, rendering, shading, and special effects.

3D modelers typically receive concept art and model sheets created at the beginning of pre-production to guide their work. Model sheets provide multiple angles of the character, including a natural pose from the front and back to speed up the modeling process. These resources aren’t always available, so understanding the concept artist's vision is crucial for accuracy. Photo references can also be used―some directors maintain a library of photo references to better communicate their vision.

The concept is then modeled in the form of meshes in a digital creation tool. A mesh is a group of vertices, edges, and faces defining the shape and structure of a 3D object. Vertices are the individual points in the 3D space that make up the mesh, while the edges connect these points to form lines. The faces are the surfaces created by connecting multiple edges together. The way a mesh’s vertices, edges, and faces are positioned is called a topology.

To get the best result in modeling, it is important to model the large-scale shapes and forms before working on the smaller details:

1. Raw shape - The first step includes silhouetting, proportions, contours, major shapes, and the object’s general forms that define the overall mesh structure. This is done using simple geometric shapes like spheres, cubes, or cylinders, or by importing pre-made shapes from a library.
2. Sculpting - Once the basic shape is created, the 3D artist refines the mesh by adding more detail and complexity. It’s a bit like sculpting: the artist simulates the physical work of a sculptor by extruding, beveling, and scaling individual vertices, edges, and faces of each mesh to give them their final shapes.
3. Texturing - Then artists add texture and color to the object. This is typically done by applying a texture map or image to the surface of the mesh, which can then be adjusted to create different visual effects.
4. Retopology - A step to generate a mesh conforming to the needs of rigging to provide all the necessary animation possibilities from the sculpted model.
5. Rigging - Finally, the model is rigged, meaning artists create a skeleton that can be used to animate the model. This allows the 3D animator to manipulate the model during animation like bending, stretching, or rotating individual limbs or body parts.

These steps require fundamentally different skills and knowledge, so it’s not uncommon to see them assigned to different people.

Some properties used by other departments are stored in the topology of polygonal objects: UV maps (a 3D mesh object's surface unwrapped on a 2D plane) used for texturing, partitioning used for shading, etc. The modeling department is responsible for generating this metadata.

Techniques For Creating 3D Models

Modeling usually requires the artist to define one by one the points (vertices) and segments (edges) of the polygon mesh of each volume required to represent a model. It’s possible to model all sorts of objects using this technique, but more complex use cases like modeling a character’s hair or tree leaves will require more specialized tools and techniques.

Here is a non-exhaustive list of various 3D modeling techniques used in animation projects:

• Polygonal modeling - Connecting vertices with edges to form polygons (usually triangles or quads)
• NURBS modeling - Non-uniform rational basis spline (NURBS) modeling uses mathematical formulas to create smooth and precise curves and surfaces
• Sculpting / box modeling - Using a digital sculpting tool to create a 3D object by sculpting the surface of a geometric volume like a sphere or cube. This technique is often used to create organic shapes like characters, creatures, and natural environments.
• Procedural modeling - Using algorithms to generate 3D models in batch, automatically. It's often used for creating complex yet repetitive structures like cities, landscapes, crowds, and buildings.
• Photogrammetry - Capturing real-world objects or environments using multiple photographs and specialized software to create a 3D model from the photos.
• CAD modeling - Computer-aided design (CAD) modeling is used in engineering and product design to create precise 3D models of mechanical or industrial product parts
• Subdivision modeling - Creating a low-polygon model and then subdividing it to add more detail. This is often used for creating characters and organic shapes.
• Retopology - Automatically creating a new mesh topology over an existing 3D model. This is often done to optimize the topology for animation or to create a lower-polygon version of a high-polygon model.
• Parametric modeling - Using mathematical equations and parameters to create 3D models that can be easily modified and adjusted.
• Volume modeling - This technique involves creating a 3D model by manipulating 3D volumes, such as spheres or cubes. This is often used for creating abstract shapes and models.
• Motion capture - Same concept as photogrammetry, using video formats: the animator captures the movement of a real-world object using specialized cameras and software, and then uses the data to animate a 3D model.

The modeling process typically involves using specialized software like Maya, 3ds Max, Blender, or Unity to create a digital representation of the object.

Best Practices for 3D Modeling in Animation

As a modeling artist, it’s important to keep a few things in mind:

• Keep it simple - When modeling for animation, it's important to keep the geometry as simple as possible, or at least use the right modeling technique. This helps to keep rendering times low and ensures that the model can be easily animated and rigged.
• Use proper topology - The topology should be optimized for animation and deformation, with edge loops placed in areas where the model will bend or deform.
• Keep it clean - Keep the geometry clean, remove unnecessary vertices, and use proper naming conventions.
• Use appropriate software - Different software is better suited for different types of modeling: picking the right one can go a long way to speed up and/or simplify your team’s work.

We also recommend using our production tracker Kitsu to plan ahead, gather feedback from your team, and test your models frequently during the modeling process to ensure that it behaves as intended. You should always plan a modeling project thoroughly before starting it, with sketches, storyboards, and reference images to ensure that the 3D model aligns with the overall creative vision. The use of reference images is critical for accuracy, so use as many as possible to achieve the desired outcome.

Last but not least, don’t forget texturing and shading to give the model a more realistic look and feel. You can have a look at our in-depth article on texturing and shading to get a better grasp of how it works and how it’ll improve your 3D models.

Conclusion

In this article, we covered: what makes 3D animation different, all the steps involved to build a proper 3D model, and all the techniques available to build 3D models. We wrap things through efficient best practices.

So now you know everything to jump into new emerging trends like photorealistic 3D models, VR/AR animation, and AI-generated art! 3D modeling is here to stay and you're going to take the most out of it!

If you are a 3D modeler, an aspiring artist, or someone who simply enjoys learning about the animation industry, we invite you to join our Discord community. Here, you can connect with fellow artists, share your work, and learn from others in the industry.