The CGI Animation Process

First used in the 1986 film Flight of the Navigator, CGI (computer-generated imagery) is ubiquitous these days. Some of the biggest and best movies and TV programmes are made using it, including films like Toy Story, Shrek and Despicable Me, as well as TV shows such as Love Death + Robots, Star Wars: The Clone Wars and Jimmy Neutron. Also referred to as 3D animation, the global CGI animation industry is expected to be worth $33.78 billion by 2026. But what exactly is it and how does the CGI animation process work?

Put simply, CGI animation is the creation of animated visual content using computer software. The term most commonly refers to 3D computer graphics used to create characters, scenes and special effects in films and TV shows. That said, CGI animation is often relied upon for other content too, such as adverts, video games and art.

CGI is popular because it tends to look much more realistic and is quicker to produce compared to physical animation techniques. Unlike 2D animation methods used for shows like The Simpsons and classic Disney films such as The Jungle Book, you don’t have to draw every frame from scratch as you can simply animate ‘rigs’ instead. These are 3D models whose skeletons can be manipulated to move in any way you see fit.

CGI is mainly created through algorithms that make complex fractal patterns, 2D pixel-based image editors that create vector shapes, and CGI animation software that can be used to animate pretty much anything. We look at the CGI animation process in more detail below.

Modelling is the process of building 3D objects that feature within an animation. This can be done from scratch using CGI animation software modelling tools or by importing 2D illustrations to turn into 3D shapes, like logos. In some cases, there will be existing CAD (computer-aided design) files to work with, but these often need refinement for use in animation and sometimes contain way more information than you actually need.

The actual modelling process can be carried out in multiple ways. For example, you could use 3D digital sculpting, which is akin to real-life clay sculpting. Here you utilise brushes and tools that push, pull, pinch and smooth, allowing you to easily create real-life textures and objects. Another popular method is laser scanning, where a real object is laser scanned to create a digital version of it. While the scanning process is simple, creators must be careful to clean up the object’s geometry so that it looks realistic.

This is where materials are added to the 3D objects to help make them look real. Often animated objects have a default grey colour and require you to put 2D images of the desired material on them. So, say you’ve just modelled a table, for instance, you can throw a wood material on there and, hey presto, you now have a photoreal table (well, not quite yet — we’ll explain more below). There are many sites out there with libraries of high-quality textures you can purchase. This includes Poliigon and Greyscale Gorilla, where you’ll find everything from wood and stone, to cotton and liquids.

One of the most important elements for achieving a photoreal look is lighting. In the same way lighting can result in certain effects on a film set, you can create the mood of the animation by adjusting the size, number and direction of lights you use. The terminology in CGI animation software is much the same as in film production, with softboxes, spotlights and area lights all used to create different looks on your 3D film set. You might want to go soft and bright for a beauty product, or dark and moody for a new tech product, for example. The way you choose and manipulate your lights will determine the look. Get it wrong and you won’t even reach the depths of the uncanny valley, let alone achieve photoreal greatness.

To be able to see what the viewer will see, you will need a camera in your 3D scene. You can choose a regular camera that moves freely or a target camera that is locked to aim at a particular point in your scene. There are a whole heap of different camera rigs that people have built for certain purposes, such as cranes and steadicams.

This is the fun bit where you make the 3D objects move. Usually involving a timeline within a 3D application, you set keyframes at different points along the timeline, locking the position, rotation and scale of an object at that moment. You then set another keyframe a few seconds along the timeline with a different position, rotation and scale, and there you have it: an animation. Animating the camera is also a really important part — you’ll rarely see a CGI animation with a static camera.

Not essential to all CGI (in fact, more of an offshoot if required), simulations are how you can create realistic liquid, fire, smoke, and other more abstract swirling effects. These animations can often be quite hard to achieve, however, though there is simulation-specific CGI animation software that can help. For example, RealFlow is often used in the movie industry to simulate fluids and other special effects, while Kameleon FireEx is a popular fire and gas simulation programme.

Rendering is the process of putting everything into files that you can actually show people. It’s like developing a photograph from film or baking a cake once you’ve thrown all the ingredients in. You just sit back and wait for the oven (computer) to bake (render) the cake (animation). Like lighting, rendering is another area that requires a lot of knowledge and skill in order to achieve a photoreal look. Almost all types of CGI animation software include a renderer within them, but most animators now use an external renderer instead for an optimal final product. Popular choices include Redshift, V-Ray, Octane, Cycles and Arnold. There was a huge shift from CPU (central processing unit) to GPU (graphics processing unit) rendering a few years back, but that’s a whole other blog post.

Composting is the final part of the process. It involves refining the look of the things you’ve rendered. A 3D render is typically formed of a number of passes — layers of information that you can use to change how particular parts appear. Shadows, lighting, reflections, refractions, colours, depth of field and motion blur can all be tweaked in the compositing phase to create the perfect final look.

So there you have it. This is by no means an exhaustive list of every detail of the process, but all CGI animations will require most, if not all, of these steps in a similar order.

Happy animating!