Rise Nagin has established an international reputation for the excellence of her fiber art, but a large work created for her splendid solo exhibition at the Three Rivers Arts Festival Gallery, Downtown, surpasses expectations.

The multilayered, site specific installation, "heliotaxis," stretches floor-to-ceiling and wall-to-wall on the Liberty Avenue side of the second floor gallery.

Colorful organic shapes are stitched or glued to diaphanous silk organza panels and at times appear to be floating in the space at room's edge, somewhat like a pond titled upward, its creatures magnified.

Some of the forms have an abstracted figural aspect, while others of this fanciful realm are amalgams of plant, animal, even archetypal forms.

The biomorphic shapes appear untethered in indeterminate planes, calling to mind the paintings and tapestries of Joan Miro, a Surrealist who practiced "automatic writing" in order to tap the subconscious. There is also, certainly, a visual connection with the celebratory and expressive cutouts of Matisse's later years.

Behind the installation, a bank of windows provides an ever-shifting component integral to the conception of the piece.

"Heliotaxis" is the scientific term for the tendency of many plants -- and some animals -- to turn toward the light. As the day dims, portions of the work are highlighted or recede, and supplemental lighting by Stephanie Mayer-Staley plays a more apparent role.

For Nagin, the installation exudes "a sort of meditative calm" reminiscent of when one is sitting beneath a tree and looking up through its branches at the light shining through the patterns the leaves make.

On a near wall the working drawing for "heliotaxis" is displayed, and one can gain a sense of Nagin's process, the individual forms being moved about until a pleasing balance is reached, among themselves and across panels.

Other fiberworks, while smaller, are no less complex, their appearances simultaneously solid and gossamer, like ethereal moments that curiously persist. Layers of airy fabric, their luxurious colors carefully chosen, build like paints on canvas, creating pockets for light to settle into, or projecting a glow that grows from the interior through a series of nuanced veils.

There is a liturgical quality to the latter, reflecting the notion, prevalent in religions as diverse as Roman Catholicism and Esoteric Buddhism, of a mysterious presence that is kept covered and only periodically revealed.

The title as well as the substance of "codex: mandala + cross," a series of 18 15-inch by 14-inch fiber pieces, confirms Nagin's interest in exploring sacred and ancient symbology. The latter and "verso," a series comprising 10 similarly-sized panels, as weightily dark as "codex" is sun-infused, also raise the issue of knowledge, how it's represented and codified. Their mystery lies in finished and different, but unseen, backs.

On one wall, several intimate works on paper are graphic yet lyrical, their abstract designs suggesting, among others, the fabric patterns of early and/or tribal societies, microcosms seen through a microscope, and an aerial view of an archaeological dig. The artist cites interests as widespread as alchemy and the plans for medieval cities that she saw when touring Europe.

Nagin's background is in painting, and she says she's always thought of herself as a painter. That explains the comfort level and fluency evident in these handsome, seemingly simple but carefully composed and colored works. Her training, received at Carnegie Mellon University, also informs her approach to fiber and is a major factor contributing to the individual vision reflected in her tactile and refined works.

Nagin is represented in such collections as the Smithsonian American Art Museum, Washington, D.C.; the Museum of Contemporary Arts and Design, New York; and the Philadelphia Museum of Art.

She's exhibited nationally in venues such as the Textile Museum, Washington, and internationally at such sites as the Craft Council Gallery, London; the Musee des Arts Decoratifs, Paris; and the Museum of Art and Design, Helsinki, Finland.

As recipient of the first Quilts Japan Prize in 1994, Nagin was flown to Japan for one and a half weeks to speak to groups about quilting and to be shown historic and craft sites. Tadanobu Seto, a publisher of textile arts books who established the prize to promote exchange between Japanese and American quilt makers, purchased Nagin's quilt, "Target: On the Beach."

She was the Pittsburgh Center for the Arts 1993 Artist of the Year, and regularly exhibits locally.

While some claim that an artist has to move to New York or a similar large art center to succeed, Nagin has established and maintained a place in the international theater of ideas, dialogue, exhibition and collecting from her Pittsburgh base.

The exhibition continues through Jan. 13 at 937 Liberty Ave. Hours are 10 a.m.-5 p.m. Monday through Friday and by appointment. It will be open 6 p.m. to midnight Dec. 31, First Night. The gallery will be closed today through Dec. 26 and January 1-2. Admission is free. More information: 412-281-8723 or www.artsfestival.net.