Four uncommonly good artworks exhibited Downtown provide the lasting impressions gained from a novel and enriching experience.

	"Ultra-Nature 2006" was conceived as a "virtual garden" by Miguel Chevalier. The 60-foot-long interactive projection is at Wood Street Galleries. Click photo for larger image.

"Ultra-Nature 2006: Miguel Chevalier" is at Wood Street Galleries and "Apophenia: New Works by Keny Marshall" is at SPACE, both through Dec. 31.

Chevalier, who was born in Mexico City in 1959 and has lived in Paris since 1985, is internationally recognized as a virtual and digital art pioneer.

The show's title work -- an alluring, 60-foot-long, interactive projection conceived as a "virtual garden" -- was created for an exhibition at the Sejul Gallery in Seoul, Korea. Other manifestations have appeared in venues as wide-ranging as Oslo, Paris and Buenos Aires.

A brilliant sky-blue background is used for the first time at Wood Street. Upon this digitally grows an ever-changing, colorful array of plant-like forms, many derived from recognizable species but altered dramatically by oversized scale and light-enhanced, vibrant color.

The thickness of patterning, fed by four projectors, varies. At one moment, the plants are spaced in a series of variously embellished verticals. At another, surges of color and form overlap in a way that suggests abstract expressionist painting.

Add to this vision constant lilting motion, as if the botanicals are caught in the gentlest of breezes. A comparison to dance is not unfounded.

The whole may be influenced by visitors passing beneath two ceiling-mounted motion sensors.

The plant mannerisms are drawn from the natural world, thus underlying this virtual world with experiential credibility and influencing the way the piece is perceived.

Each plant grows from floor to ceiling. The often subtle variations in the way they move is a result of the growing habit of the actual plant they're patterned after, sort of like fast-motion nature films of germination or blossoming.

"RGB Land," which debuts here, is a markedly different work. The sound is bombastic; the colors, abrasive; the motion, dizzying.

Here the viewer stands on the brink of what appears to be a panoramic Western landscape, akin to Monument Valley, that races toward him/her at a rapid pace, simultaneously diffusing out to the edges. It's entirely colored in red, green and blue.

The piece is accompanied by electronic music, including a choral component that is reminiscent of both Hollywood biblical epochs and blockbuster science fiction. The gallery's comparison of the work to that of Caspar David Friedrich, who symbolically located the divine in nature, is thus credible, but there is little comfort in this disorienting ground.

"RGB Land" looks as if it was filmed from a small plane, but it's entirely computer generated. The mapping device, therefore, defined the landscape, rather than the reverse norm. Also noteworthy is that neither of these works is a repeating loop but both are live, constantly being created by their programming, gallery curator Murray Horne points out.

Marshall has installed two large sculptures at SPACE, their aspect scavenged and raw, a casualness sophisticatedly plotted by the innovative Pittsburgh artist.

Room-sized "3D pipes" comprises various found pipe, valves and gauges welded together and otherwise assembled. Rust and paint remnants become formal elements.

On the gallery walls, bold drawings of details of the sculptures pull -- draw -- the exhibition parts together and also call attention to how much like drawings in SPACE the two sculptures are.

Noticing that is another intent of Marshall's, who defines the show's title as "the experience of seeing patterns or connections in random or meaningless data."

Where "3D" is silent and stationary, "electro-acoustic experiments" is kinetic -- mechanically and organically -- and has sound.

In the center, three small puffer fish endlessly circle their large, brightly lit, globe-shaped aquarium. Other components include two monitors and eight tall horn instruments, of a sort, that appear to randomly emit sound reminiscent of an orchestra tuning up.

One notices how confined the tiny fish are in the round world that visitors orbit as they explore the piece -- and then more connections are made, to the environment, the solar system, mankind's fate.

In the midst of this contemplation, another revelation -- and readers who want to puzzle this piece themselves may want to skip the rest of this paragraph. As the fish pass two cameras pointed at their bowl, they trigger one or more sensors, activating a like number of horns. Aside from being a clever device, it also tips the role of the confined creatures, now seen as having greater influence than originally perceived, and even introducing a bit of Friedrich.

While both artists incorporate science and technology into their art making, Marshall's work is as low-tech as Chevalier's is high; the artist's hand evident in the former's and obliterated in the latter's. Marshall's aesthetic incorporates early assemblage artists, composers like John Cage and contemporaries like Tim Hawkinson, while Chevalier's reflects the sounds and landscapes of Hollywood and video gaming with undercurrents of transcendentalism and Monet.

Such are the connections of contemporary sensibility, here so creatively packaged.

"Ultra" is at 601 Wood St. Call 412-471-5605 or visit www.woodstreetgalleries.org. "Apophenia" is at 812 Liberty Ave. Call 412-325-7723 or visit www.spacepittsburgh.org. Admission is free. Hours for both are noon to 8 p.m. Tuesdays through Thursdays and noon to 10 p.m. Fridays and Saturdays. They will be closed Dec. 25 and 26.