Up to here, we have covered pre-production and production phases of the 3D animation pipeline. Next comes post-production. At this stage, the final touches are added to the project to make it look polished and professional. Post-production artists have a number of tools that can make up the look of a project in whatever way they want without having to render the whole project again.
The first step of 3D animation post-production in 3D animation studios is called compositing. It involves taking the render passes from the production stage and combining them together or mixing in additional images or adjustments layers, to create a more cohesive composition.
The process can be as simple as putting two layers together, or as complex as matching hundreds of layers and adjusting their properties such as depth of field and color. This is where the final look of an animation really comes together. Some 2D visual effects can also be added if necessary.
Here, we’ll take a look at an overview of compositing and how it fits within the realm of 3D animation.
What is compositing?
The definition of compositing originates from photography; meaning combining two or more images to make a single one. Generally speaking, compositing is the combining of visual elements from separate sources into one image, in a way it creates the illusion that all those elements are parts of the same scene. Compositing can include special effects, stage extension, environment creation, blue/green screen replacement, etc. In 3D animation, compositing is about combining two or more render passes or adding layers to create a single image or series of images with predefined properties.
Pre-digital compositing techniques go back as far as 19th century. But most compositing today, including 3D animation, is done through digital tools. Several compositing programs can be used to touch-up and edit digital renders or add special effects by compositors in an animation studio.
Why do we use compositing in 3D animation production?
Compositing stage can save huge amounts of time and money in a 3D animation studio. During the rendering procedure, the computer reads large amounts of 3D data and makes a lot of calculations to be able to create 2D images or frames. That’s why the rendering process can be very time-consuming; even with the most powerful hardware and software available in the market.
The rendering of a 3D scene is often performed in separate layers or Render Passes. Render passes give more control over different aspects of a scene. For instance, each object can be rendered separately in different layers, hiding the rest of the objects in the same pass. This way, you will be able to fine-tune your lighting, coloring or other adjustments, create rendered variations and choose the best one without having to render the entire scene again and again.
Now, imagine these were to be done in 3D: The whole rendering process had to be repeated multiple times; imposing an excessive amount of unnecessary burden to the animation studio in terms of resources. That’s why the final rendering occurs after the compositing stage in most 3D animation studios. For example, if part of a scene like a single 3D asset needs to be changed, only the part that needs to be corrected will be replaced instead of re-rendering the whole scene.
On the other hand, final-rendering a sequence with 2D images after the compositing stage will be much faster than rendering the 3D project; because there is no need to process all the 3D data regarding each and every 3D asset in the scene. The sequences of render passes and layers will be combined together, color corrected and tweaked; then forwarded to the end of the pipeline for the final rendering.
The following is an example of compositing for a short 3D animation; visually explaining how it’s done in a nutshell:
The job of a compositor in a 3D animation studio
The compositing department of a 3D animation studio is responsible for bringing together all 3D elements created by the previous departments involved in the 3D animation production pipeline (including rendered computer animation, 3D visual effects, graphics, 2D animation, live action, static backgrounds, etc.) and creating a screen-ready render.
A compositor’s job is primarily to bring the quality of shots to the expectation level of the decision-makers and maintain it throughout the project. Integrating the 3D scenes while keeping an eye on technical and artistic aspects of the output is a huge part of a compositor’s responsibility in a 3D animation studio. Enhancing the colors, lighting, adding motion blur, 2D effects etc. would be of great help to achieve this objective.
Moreover, being able to work with relevant departments in relation to compositing is a necessity. So maintaining productive communication among the team and a good relationship with other teams is crucial for a compositor role in an animation studio.
Every scene of a 3D animated video is often rendered in multiple layers or render passes. These layers are going to be united again in Compositing stage. Compositing is the first step in 3D animation post-production, which involves taking the render passes from the production stage, combining them together and mixing in additional adjustments, images or layers, to create a more cohesive composition. Just like lighting, VFX and rendering, compositing is closely tied with 2D VFX, color correction and final rendering.
Compositing stage can save huge amounts of time and money in a 3D animation studio. The tools and techniques available to compositors make it possible to make adjustments to the look of a project without having to re-render it.
Creating “something” out of “nothing” has always been the greatest joy of my life. “Content Creation” is the offspring of my innate characteristics including a never-ending thirst for painting, poetry, photography, music and writing.