Mocap is Xsens equipment for VFX production. Personal experience of use

Technology motion captureor mocaphas been in existence since the 1970s. It is used by large companies in the production of films and computer games, achieving the most realistic animation. We recently purchased an advanced version of such Xsens brand equipment for our studio. Let’s talk about our experience in this article.

How it works?

The first Motion Capture complexes were optical. Their principle of operation to this day is that several cameras record the dynamics of reflective markers distributed over the body of a moving “actor”.

Putting on the suit and sizing
Putting on the suit and sizing

Equipment xsens is an inertial system. It uses accelerometers and gyroscopes to measure positions and angles of movement.

Inertial tracking has been made possible by advances in micro-sensor technology. A speed gyroscope measures angular velocity. The silicon accelerometer measures accelerations, including gravitational acceleration g.

Optical systems lose to inertial ones in transferring the accuracy of movements. Camera tracking is largely based on computer vision techniques. Structured lighting systems use lasers or beams. Optical systems suffer from line-of-sight problems whenever the necessary light path is blocked. For example, interference from other light sources or reflections.

Filming
Filming

What is the equipment made of?

The Motion Capture equipment consists of a lycra rugged suit, trackers, battery and bodypack (computer). 17 trackers located throughout the body synchronize their data using gyroscopes, accelerometers and other technologies for high accuracy of transmission of joint angles.

Mocap reads any human movements. The exception is if there is no technical movement, and not the actual one. For example, rollerblading.

The data from the sensors is transmitted to the computer using a wifi router. They are immediately processed by their own software. The software is called Animate Pro. The data is exported to different formats, including FBX, which makes it possible to use them in any 3D program and game engines.

Filming process

The minimum required for filming is the presence of an actor and a computer. Of course, it is more convenient to shoot in a studio with lighting, as we did. But this is not a prerequisite. It all depends on your tasks, the range of motion of the actor and the desired result. You can shoot in a small room or in a stadium.

Motion recording and animation with real-time avatars
Motion recording and animation with real-time avatars

You don’t need a van to transport equipment. The suit is a small (hand luggage size) durable suitcase on wheels, weighing up to 8 kg.

The filming process itself consists of 3 stages: calibration, shooting, cleaning of the material.

1. Calibration. For 15 seconds, the actor first stands, then takes a few steps and you’re done! There are errors. After long sessions, it is advisable to do a new calibration.

2. After setting, the movements are recorded directly. As an experiment, we conducted a live broadcast, where we tested mocap in action with actors and avatars.

3. Manual cleaning. It is needed in any case, but the result of the initial data is much cleaner and better than similar products and optical systems. The data may be worse if the calibration has not been done for a long time.

Do I need to be a mocap expert to work with it? No. With a short and simple basic training, animators, technicians, and artists can work with costumes. The suit is easy to handle, making it accessible to everyone.

Pros and cons

Pros:

  • remote data recording

  • fast calibration speed and ready to go

  • the ability to use the suit on your own, without outside help

  • friendly software interface

  • possibility to use data recording without PC and software using bodypack

  • synchronization of up to 4 actors in one scene

  • use of the suit anywhere, even at home, even in the forest

  • high-quality reprocessing and clean data ready

  • large knowledge base and documentation

  • 24/7 customer support

  • available equipment options

Minuses:

  • no orientation in space, like optical motion capture

  • high cost of MVN Link configuration

  • applicable only to humanoid characters. Quadrupeds and other animals cannot be used

Now our studio is working on creating CGI / VFX videos, where all character animation for these projects will be created based on mocap technology. We will share the process of work, subscribe and stay tuned)

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