Why the process of Rotoscoping is important.

Rotoscoping is an important process within the pipeline of visual effects and a important process when creating a 3D configurator. Whether you need to remove elements from live action material or add elements, you need to have a deep understanding of this very important technique.

Through this article, we want to give you a deeper understanding of the process of rotoscoping and how you can use this technique in practice. We would also like to give you some helpful practical tips.

In its traditional use, Rotoscoping meant tracking live action material frame by frame for use in animated films. In this way, the animator could create very realistic movements by tracking the actor in the scene. You can imagine it as today’s motion capture, so to speak. With visual effects, though similar, the process has a different purpose. Rotoscoping for VFX is used to create a mat or mask for an element so that it can be pulled out to place it on another background, or faded out so that colors, for example, can be changed.

The Rotoscoping Artist (Roto Artist for short) tracks an object using a series of tools within the compositing software to create a new alpha channel for a specific part of an image sequence or video. Unlike computer-generated images, which can easily add an alpha channel to their images, the material captured directly from a camera has no alpha data, so the Roto Artist must manually create this alpha by tracking the elements within the video. A Roto Artist must create different shapes around an object and animate these shapes to match the motion on each frame.

Depending on the complexity of the shot, the Rotoscoping process can take hours or even days. Using blue and green screens, rotoscoping still plays an important role in the production of visual effects. Since Rotoscoping is used in almost every film and television show that uses visual effects, it is not surprising that Roto Artists play an important role within the VFX pipeline. There are many different compositing applications that have the necessary tools to get started with Rotoscoping. Rotoscoping is an art form in itself, so mastery does not happen overnight. Therefore, you should first acquire solid basic knowledge.

Keep the checkpoints to a minimum. When you first start learning rotoscoping, your first act may be to create as many points as possible to correctly represent the element within the material. However, it is better to use a minimum number of points and only what is needed to track the topic. When the contour of a mat changes across multiple frames, it can make a nervous impression when played back, and it’s much harder to keep track of all the dots. A good technique is to find the most complex shape the object is in and sketch it first so that you know most of the points you will ever need for this rotoscope. The rotoscoping tools in your compositing software have very powerful curve manipulation functions that are able to generate complex curve lines with a minimal number of points.

Create separate shapes. If the object or person has a very complicated shape, do not try to use one shape for the entire subject. It is often best to separate different limbs, fingers, etc. in different subforms. For example, parts that are to be moved independently, such as the hand, finger, forearm, and arm, should be separated. If you were to try to follow the outline of a complex movement, such as two characters fighting, it would be almost impossible to accurately follow the actions with a single outline. Use as few keyframes as possible. If you animate the rotoscope to follow the movement of the element in the footage, you usually don’t have to create a new keyframe for each frame. The computer automatically interpolates between keyframes and generally delivers the desired results. Just as an animator would draw the key poses first, you can do the same with rotoscoping. Find the frames that move the most and adjust the shapes accordingly. If the outline doesn’t perfectly match the subject, you can then go in and add another keyframe to make this adjustment. Study the footage you will be working with before starting rotoscoping. Are there any major directional changes? Are parts of the subject obscured by other elements within the scene? Are there large camera shake that can be stabilized to make the rotoscoping process easier for you? If you know the footage, you can better determine the timeframe for the project and the best way to rotoscope. Consider the rules that apply to animation because rotoscoping is a kind of animation. You create keyframes and animate the outlines of the subject within the material. The same way Animator thinks about arcs as you would about arcs. Finally, the animation principles are based on real studies and you will see these principles in action as you follow their material. By thinking about these things while rotoscoping, it will help you to place the keyframes in the right place and find out early on where the ease of the inputs and outputs would occur in the footage and how your keyframes should be placed to follow the subject. Rotoscoping may seem boring and not so exciting, but it is important for any VFX designer to know, even if you are more of an effect person who likes to create the explosions, you should know this technique and the meaning of it in the pipeline. The next time you’re in charge of rotoscoping, try implementing some of these tips to improve your work processes.

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