Creating virtual characters

The history of art has put it clearly: the human figure has been one of the most valued (and most complex) resources for the creative process. While for millennia the reproduction of the body was limited to two-dimensional representations of the body, the Renaissance posed a dramatic change of vision by introducing the study of perspective and light, adding a third dimension to the human figure, albeit in a still static way. The advent of photography, film and television not only added depth and realism to the representations of the body, but also allowed its movement to be fully reproduced.

However, perhaps the most innovative advance in this regard was the computer, allowing to create characters with their own life, with lighting conditions, textures and movements very interesting for contemporary creators. Soon the name of "virtual characters" was given to these types of figures that seemed to imitate, although awkwardly at first, the gestures of real human beings. Behind this creative and scientific medium, there is a key tool: motion capture.

"Motion Capture" basically involves capturing the characteristics of the movement of a real object, to transfer it to a computer-generated object. Roughly speaking, the operation of this process is relatively simple:

1. Special markers are placed on the actor's joints and main points of movement, and usually on a blue background (special for chroma-key processes). Another possibility is provided by mechanical - magnetic capture systems, which through a "suit" consisting of rigid modules, joints and cables, faithfully record the movement of the actor.
2. A special hardware then records and analyzes the position and orientation of these markers over time, thus generating a set of motion data, known in the technical realm as "motion curves."
3. This information is transferred to a three-dimensional character, previously modeled on the computer.

Although this form of production has been studied since the 80's, until a few years ago the use of "Motion Capture" was restricted to the direct transfer of animation parameters, underusing all the true potential offered by the tool, and ignoring certain problems offered by the movements of real objects. Consider, for example, the movement of clothing with respect to the body, which tend to move separately: the swaying of a skirt is generally opposite to the movement of the figure. Over time, the animators found that the secondary actions of the characters were many times more definitive to produce more truthful and dramatic figures... paradoxically, more human. With the progressive improvement of software and hardware in the last decade, the technique has not only allowed to satisfactorily solve these problems, but has also allowed the creation and animation of characters that are increasingly closer to the real human being. At present, such technology is used by numerous special effects and 3D animation companies (LucasFilm, Pixar, Industrial Light & Magic, etc.) to produce realistic animations in several films: Star Wars I, Titanic, Species, Batman, Terminator 2 and, more recently, Final Fantasy , progressively have opened a new dimension to the creation of virtual characters, and allow us to think, without fear of exaggeration, that at the turn of a few years many human actors could be replaced by their virtual counterpart.

The advantages of this technique are evident, not only for the reduction of costs in production, but also in several aspects:

1. Through normal 3D animation techniques an average of 3 final seconds can be obtained from an animated figure per day. With "Motion Capture" between 2 and 20 minutes can be achieved in the same period of time, depending on the complexity of the animation. Think, in this sense, how many more years it would have taken for final fantasy, 108 minutes long, to reach us if it had been made entirely with traditional methods of 3D animation.
2. In many cases, Motion Capture becomes a mandatory technique, especially in situations that would be impractical or too dangerous for real actors. In the movie Titanic, for example, many of the characters who fell from the ship were created in this way.
3. The same film presents us with another advantage: in many of the scenes virtual characters were used as "extras", or also camera flights on a virtual ship. In this way, actors, models and virtual cameras come together to create totally photorealistic scenes.
4. The creation of virtual characters has an application of special interest for television producers, because it allows the creation of presenters, without the need to memorize a script or without the fear of making mistakes. Take, for example, the creation of a virtual Larry King, on January 31 of '99. Actor Harry Shearer gave life to a gigantic cartoon of the famous television host during the Super Bowl in Miami. The actor improvised his character from a high-tech studio located not far from the stadium. The virtual Larry King appeared 10 times on screen during this event, and conducting interviews with Stevie Wonder, Ivander Holyfield, Kiss, Don Shula and others.
5. Motion Capture's technology has a growing number of applications in fields as different as the Web (especially for virtual hosts and virtual postcards, thus giving a more "human" element to the Internet); in biomechanical analysis (for the successful design of prostheses); in engineering and design (to produce ergonomic objects); in education (through interactive virtual instructors), in games and in virtual reality.

Gipsy 3 is a mechanical capture system produced by the companies Analogus and MetaMotion. It consists of a piece of hardware that is placed by modules, like a suit, on the model of which you want to capture the movement. It has a very wide range (1/2 mile), superior to other optical and magnetic equipment. It also has the great advantage of being an independent piece, which moves next to the body and does not need specific environments, so Gipsy is ideal for capturing movements that require large areas of land. This part works in connection with any PC through a serial cable, and its batteries last about 4 hours. Finally, this hardware not only has its own application, but also supports any of the most popular software packages for Motion Capture and 3D human figure modeling (Kaydara FilmBox, DreamTeam Typhoon, Famous 3D, Maya and Poser 4)

This app is undoubtedly one of the best in the field of animation. Its ability to immediately draw medium-resolution characters (up to 20,000 polygons with a good acceleration of the OpenGL 3D standard) make it an excellent choice for event animation for real-time Broadcast. Additionally, it provides an excellent visualization of motion capture information, and its availability of platforms (Windows NT and SGI Iris) make it a leader for the development of animations with this type of technology.

Among its most important features, we have the fact that it supports the largest number of capture devices available in the industry. It also offers extensive format import and export capabilities, which makes it ideal for the production of virtual characters for games, broadcast and cinema. It also allows the movements of several actors to be captured simultaneously.

Its package of advanced functions are really impressive, as it assigns the movement data to characters of any shape, weight or size, providing a precise fit between real actors and virtual figures; fixes failures in the capture and re-elaboration of lost points, a special function for optical devices that work on the basis of reference points; provides automatic figure stabilization tools in walking, jumping and running processes. Its built-in audio feature and Lip-Sync allow full synchronization of multiple audio channels in conjunction with 3D animation.

Life Forms Studio has a significant number of features that ensure its inclusion in motion capture studios, both large and small. You can import . BVH produced by Gipsy or Kaydara FilmBox. Additionally, it provides import and export support for the industry's leading 3D packages: 3D StudioMax, LightWave 3D, Maya, PowerAnimator, Inspire 3D, StudioPro, Poser, Cinema 4DXL and ElectricImage. Its export modules for Web and for PalmOS devices make it a tool to consider. It works for Macintosh G3, and Windows 98.

With all the benefits of real-time capture, and without the restrictions of suits, cables or battery packs, Vicon 8Rt presents a passive system of reflective markers for motion capture (optical) with a special camera of 120 Mhz. It is built on the hardware of the same company (Vicon 8 DataStation) which is perfectly suited for movies, television and games.

Its software package reconstructs multiple (2-dimensional) camera images in 3D coordinates, and a user-defined kinematic model generates the translation and rotation information for the defined segments, stabilizing data flows to ensure smooth and continuous quality of movement. In the same way, this application allows the simultaneous processing of images directed by a medium-range computer (Pentium 500 Mhz) and distributed through a variety of networked machines with 3D capabilities. Its high performance (30 frames per second) is perfect for broadcast and film productions. It operates on Windows NT stations.

Computer graphics processing technology has provided us with impressive examples of its future scope. Within this context, motion capture has been a key piece, not only in the realization of productions for film and television, but it is used recurrently on the Web, in virtual reality, in live and live events, in biomechanical analysis and even in scientific research.

More and more independent companies are starting to create real studios... in a garage and with a computer: the idea of two or three people creating a full movie is not far away, especially if motion capture is used correctly.

And although this technique certainly represents a great technological leap – which began with simple 3D "wire structures" in the early 70's to reach the powerful graphic workstations capable of reproducing shaded surfaces in real time – the current state of technology seems not to be enough: the biggest challenge is to be able to reach the immediate reproduction of photorealistic textures, without the need for tedious rendering and modeling processes.