Artistic Renderings of Dynamic Actions (Gatech)

Marcel Duchamp, Nude Descending a Staircase, 1912

Non-photorealistic rendering is a field of significant interest in the graphics community with many recent papers on such topics as rendering with simulated watercolors, creating images in an impressionist style, and automatically extracting silhouettes. We are interested in expanding this repertoire of techniques by exploring techniques that allow moving figures to be rendered in such a way that the dynamics of their movement is emphasized.

Boccinoni, Raid, 1911

One style that has attempted to render figures showing movement is Italian Futurism (1909). Although tangled up in the politics and violence of the time, the artists of the Futurism movement tried to provide a portrayal of energy and speed through their paintings, photographs, and sculpture. Many of their stylistic techniques lasted beyond the period.

Boccioni Riot in the Galleria 1910

Often their figures appear to be off-balance and leaning or falling in a particular direction (Boccioni, Riot in the Galleria, 1910 and Raid 1911). In Raid, an additional technique, "lines of force" is evident. Rays of light form multiple lines to heighten the appearance of distress in the crowd Tisdall,1978).

Balla Leash in MOtion , 1912

Another artist in the movement, Balla, used multiple images of a sparsely rendered subject to convey a feeling of motion (Balla, Leash in Motion, 1912 and Girl Running on a Balcony, 1912). And finally, Boccioni experimented with gross distortions of the shape of the muscles to illustrate the motion of a sculpted figure (Boccioni, Spiral Expansion of Speeding Muscles, 1913).

Balla, Girl Running on a Balcony, 1912

Boccioni, Spiral Expansion of Speeding Muscles, 1913

In this project, we will render motion data as animations, images, or textured statues. All the non-photorealistic rendering techniques that we develop will attempt to emphasize the motion in the scene.

Very Abstract Rendering

• to_ascii
• extreme motion blur
• counteracting lines
• camera through the eyes

• distorting time
• exaggerating joint angles to create a stronger line of action

• two models and interpolating between them based on torque

• cartoon lines of action
• streaks, streamers showing path

Visualizing Physical Parameters (Brown)

Realistic animation of human motion has a wide variety of potential applications, ranging from entertainment to sports training and medicine. Current techniques for animating human characters focus on the motion itself and typically output a rendering of the moving character. Many applications, however, especially those in the sciences and sports, could benefit from the visual display of supplementary information about the motion. For example, a visual display of weight distribution and active muscle groups could help a dancer to understand not just what a motion looks like, but how it is performed. Physically based approaches to animation such as that pursued by both Pollard and Hodgins make this type of supplementary information readily available. For example, we have developed techniques to scale simulated motions such as running and cycling to new individuals. Ground contact forces and joint torques are an intrinsic part of the simulated motions, and a user comparing the performance of different individuals would wish to compare these quantities across simulations. This information, however, is not currently provided to the user in an intuitive form.

In this project, the student will explore ways to visualize some of the physical parameters associated with a motion sequence. The goal is to provide supplementary information to help a user to better understand the motion that is portrayed. There has been very little previous work in visualizing dynamic information associated with animated human characters. Because intuitive display of this type of information is far from an exact science, this project will allow for substantial creativity on the part of the student.

Non-photorealistic, or stylized rendering techniques will be used to display the results, because they allow us to isolate the important information, as would be done in a user's manual or in a technical illustration. We will use an in-house non-photorealistic rendering system developed at Brown (Markosian, Siggraph 1997). The system is now in use by a substantial number of graduate and undergraduate students at Brown, and there will be support to assist the student in the use of this system.

The physical parameters to be displayed in this project will come directly from physically based simulations or from other sources such as motion capture data. When other motion sources are used, we will calculate the required information using techniques such as inverse dynamics, a method used in robotics to calculate the control torques needed to generate a desired motion.