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Blockbuster features and shows that display tremendous CG effects such as Avengers: Endgame, IT: Chapter 2 or Game of Thrones require a massive budget for such visuals. However, to save production costs, production companies create a rough 3D animatic of a VFX shot before sending the renders to artists and animators. This process is called pre-production visualization. It is also known as previs.

Today, we’re going to talk about the basics of pre-visualization and what it is before we explore some examples more in-depth.

Image of Spiderman on the ship in previz (above) in comparison to the finals render (below). Notice how closely the finals match to the previz render. Source:
https://www.awn.com/vfxworld/previs-plays-major-role-avengers-infinity-war

Previs (also known as Camera and Layout in animation production) is a common stage in the VFX pipeline that visualizes the shot with cost-effective 3D assets and animation. Previs usually starts when the previs supervisor is given storyboards or script. Then the shots are assigned to previs artists to create their shots by animating 3D rigs and assets. After the shots are completed, they are then compiled to form an edit sequence. Once the edits are approved, the previs renders are then distributed to VFX studios and film sets to match their work closely to the previs.

Diagram of the VFX pipeline production. Previs plays a role in pre-production as the client has the flexibility to make changes with the rough animatic. Source:
Virtual Reality Rehearsals for Acting with Visual Effects by Rozen Bouville Berthelot

Once filming begins, the previs production moves on to post-visualization (postvis). In this stage, live-action plates are integrated with 3D renders from the previs. This allows the production to quickly preview the film before implementing final VFX.

Postvis helps the director visual aid for what the shot would look like when the live-action is integrated with the visual effects. Source:
https://www.awn.com/vfxworld/previs-plays-major-role-avengers-infinity-war

At times, the placement of characters in a 3D environment are vital in telling a story. As with the case of Thor: Ragnarok, the final battle takes place on Bifröst bridge from many different directions. It is hard to keep track where the characters are when there are many events happening at once. By analyzing the technical aspects of previs (known as techvis) we can accurately plan the placement of the characters to keep the storytelling consistent.

Top view of Asgard’s Bridge Battle, visualized with 8-bit graphics and sound effects. The full video can be seen here. Source: Polygon:
“Thor: Ragnarok used some 8-bit inspiration for its final fight” by Susana Polo

Previs is a cost-effective process that helps visualize key VFX shots in the pre-production stage. Many notable franchises implement previs as a tool to ensure the live-action and the CG elements are aligned to the director’s vision. That being said, previs is not limited to live-action projects. In animation production, previs becomes camera and layout (or also known as 3D animatic) as illustrated in an example below from Monsters University. Most of the time, the rigs for camera and layout are economical enough to make a few key poses.

Source: Digital Arts Online

So why previs?

Just by watching the previs reel, it can be said that the quality of animation is up to par in comparison to the finals. Even though animating for previs is not as skill-intensive as animating for finals VFX, previs still demands a great deal of knowledge in cinematography, photography, lighting, and staging. From what I have learned, being in previs gives you the most freedom in being creative. You can choose what to put on screen and conduct what actions and events are happening. Anything later in the pipeline will essentially follow the previs. Even the directors have a board of previs screenshots printed on-set, and cross each of the images after the filming is done. Previs, like storyboarding or animatic, conducts a major part of the VFX production creatively.

How to enter into previs?

If you love directing action-heavy scenes, car chases and superheroes, (or even playing action figures!) previs may be the right position for you. You will use a lot of motion-capture since most of the projects involve live-action performances. However, your best-selling point is camera movement. An ideal demo reel for previs would be an animation reel that has a realistic camera movement – a kind of movement that has weight, overlap, and follow-through when filming the characters. Animating cameras require just as much attention as animating characters: the timing and the arc of the camera movement need to read well for the audience. I hope that this month’s blog inspires prospective artists an filmmakers in learning more about previs as it is also one of the easiest areas in VFX industry to break into.

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