Painting with Feeling.(research at University of North Carolina at Chapel Hill)(Technology Information)

With a haptic interface and virtual paintbrushes, artists can apply a traditional touch to their digital creations

In order to improve the art of digital painting, more attention needs to be focused on the craft of painting, according to researchers at the University of North Carolina at Chapel Hill. The art of painting refers to the aesthetic aspects of of the final product, while the craft of painting deals with the study of materials, including paint medium, tools, and methods.

To an artist, the art and craft of painting are closely related. Unfortunately, that connection has not been transferred to the computer graphics realm, according to UNC's William Baxter and Vincent Scheib, who, under the advisement of professors Ming Lin and Dinesh Manocha, have designed a novel interactive painting system to serve as a conduit to both art and craft. Rather than focus primarily on the rendered appearance of the final product, as is the case with most of today's digital palm tools, the new system, called dAb, pays due attention to recreating the sight, touch, action, and feeling of the artistic process itself.

Artistic Touch

To incorporate such considerations, dAb uses a physically based, deformable brush model integrated with a haptic interface that is programmed to provide the force and tactile cues conceptually equivalent to real-world painting.

"The haptic stylus serves as a physical metaphor for the virtual paint brush," says Lin. "It takes in the position and orientation of the brush and displays the contact force between the brush and the canvas to the user." The brush bristles are modeled with a spring-mass particle system skeleton and a subdivision surface, enabling the creation of a large selection of brush types and a wide variety of strokes and painterly effects.

Developing the virtual 3D paintbrush required both a geometric representation and a physics-based model for its dynamic behavior. The design was constrained by the requirements of an interactive haptic painting system. "The real challenge was developing a simulation method that was stable enough and still computationally fast enough to maintain interactivity," says Baxter.