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The detailed guide to previs

Jonathan Rawlinson 22 May 2020

Every step in the TV production process plays its own important part in the creation of the final product. No matter the production, there is an intricate machine of moving parts going on behind the scenes that eventually coalesce to create something special.

Today, there is one area in particular we want to focus on. It is a really useful planning tool for any production that can never be underestimated. We’re talking about ‘previsualisation’ – previs for short.


Defining previs 

The Visual Effects Society (VES), the Art Director’s Guild (ADG), and the American Society of Cinematographers (ASC) define previs as a ‘collaborative process that generates preliminary versions of shots or sequences, predominantly using 3D animation tools and virtual environment’. They also say ‘it enables filmmakers to visually explore creative ideas, plan technical solutions, and communicate a shared vision for efficient production’.

Previs is a valuable communication and collaboration tool for directors, writers, producers, VFX supervisors, directors of photography (DOPs), and production designers – plus many more involved in a production. Previs helps everyone visualise and plan for a shot, sequence, or even an entire production, as now happens with animated features and productions that use virtual production pipelines.


The different types of previs

Like many other areas of VFX, previs has grown to encompass an entire suite of terms. Along with typical previs as defined above, the VES, ADG, and ASC also recognise these sub-genres of previs:

  • Pitchvis – As the name implies, pitchvis will help visualise the potential for a project while it is still being financed. Sequences or environments for the project will be created to help secure finance or a green light.
  • Technical previs (techvis) – This version of previs incorporates actual camera, lighting, design, and set layout information to show how a shot can be realised using real-world measurements.
  • On-set previs – This creates real-time visualisations on set to help the director, VFX supervisor, and crew understand how and where any 2D or 3D VFX elements will appear in a shot by combining live-action footage with 2D or 3D elements to get immediate visual feedback.
  • Postvis – This happens in post-production once you have shot your master plates. There are more evolved 3D animation ‘blockouts’ of creatures or other 3D assets that need to be incorporated into a scene. Postvis can be helpful during post-production to enable VFX producers to get the ‘sign off’ from executives and to help with planning and budgeting for complex scenes.


Previs techniques

Before digital technology came to prominence in the film and TV industries, filmmakers used a wide variety of techniques for visualisation. One technique still in common use is to create storyboards. These are often also used to help create a visual idea for a CGI previs sequence.

Other techniques that are used include:

  • Animatics – An edited assembly of storyboards and other key frames from an animated film or sequence to give an idea of the pace and look of a film.
  • Riopmatics – An assembly of existing live-action footage, often used to help plan an action sequence. George Lucas famously created a ripomatic of WW2 plane ‘dog fights’ to help plan for the original 1977 Star Wars.
  • Slap comps/precomps – These are often created by VFX editors or the editorial team during post-production to help tell a complete rough visual story for a production. These are often 2D backgrounds or matte paintings for early assembly edits of a production.


Who uses previs?

Previs has traditionally been used as a planning tool. The VFX supervisor and producer will commission previs of complex scenes or shots, usually involving 3D animation or set builds, to help the director, DOP and other head of departments understand what the final shot or sequence might look like.

For example, you might have a flying creature, such as a dragon, which flies through a CGI cityscape while your live-action cast members look on. In order to understand how and where the dragon will fly and ‘behave’, previs can be a helpful tool for the team to understand how to frame shots, what camera lenses to choose, and where greenscreens might be needed to insert backgrounds later. Previs can be helpful for the whole team to understand the scale of a creature or cityscape in a shot. By planning ahead, you can ensure you shoot the right coverage and framing for your CGI creatures and sets.

For producers, previs is often a tool that helps control costs. CGI and animation are expensive, and by creating previs of a key scene, you can help control the shot count and the overall cost of any animation. Previs is also helpful to producers for both internal ‘selling’ of key sequences to financiers, but also for creative and budgetary sign-off during post-production. It’s far better to get ‘buy-in’ from your funders to the overall pace and look of an animation sequence before you start the expensive process of full animation.

For Directors, DOPs and production designers, previs is a creative and logistical planning tool. For this reason, it is also important that these departments are involved in the previs planning, to ensure they feel involved and can give their input on their respective areas.


What are the benefits?

Two key benefits of previs are the time and money it can save you. It’s no wonder it has been a reliable staple of the production process for so long. It is a great way to condense creative and logistical approach visually, which helps ensure the entire production team understands the overall vision for a sequence or shot. You can collect the scattered thoughts from you, your team, and your creative partners and bring them together to create a singular, coherent vision.

By saving yourself time, you are also saving yourself money. Your budget will constantly be under intense scrutiny, and to prevent it from spiralling out of control, you can plan your future decisions down to the finest detail.

And, at the end of the day, it helps you tell your story. Be it a historical fantasy series or a whimsical space adventure, previs allows you to communicate your story visually in the most effortless way possible. 

At REALTIME, we work on all types of previs. So whether you need some postvis, a ripomatic, or some storyboards to plan your project, our team of artists, creatives, and directors will guide your project through this step with their wide range of expertise. If you would like to discuss your upcoming project, feel free to get in touch with me at [email protected].