The effects of the shattering tragedy on Sept. 11 will undoubtedly be seen in contemporary art in the not-so-distant future. But it has already created, virtually overnight, a new category of outsider art: the astounding impromptu shrines and individual artworks that have proliferated along New York's streets and in its parks and squares.

Alternating missing-person posters with candles, flowers, flags, drawings and messages of all kinds, these accumulations bring home the enormity of the tragedy in tangles of personal detail. They have also brought to its broadest expression yet the 20-year-long democratization of memorials that began with the Viet Nam Memorial, with its naming of names. The trend continued in the AIDS quilt, with its handmade images and mementos, and reached a peak of public participation with the oceanic expanses of flowers amassed in front of St. James's Palace after the death of Diana, Princess of Wales.

Still, certain works of art already on view in New York galleries registered the change unexpectedly simply because the tragedy gave everything, art as well as life, a radically different context. In ways sometimes symbolic, and in one case literal, they looked different, and meant something different, too.

Sometimes it was pure, desperate projection. Ten days ago the big grisaille image of President Bush's face that was included in the show of Richard Phillips's lurid new paintings at the Friedrich Petzel Gallery in Chelsea looked vapid and slightly sarcastic. But now, in the city that was the capital of the blue country on the post-election voting map, the painting was suddenly devoid of irony and more animated, perhaps because one looked at it harder, with a greater sense of familiarity. One could read dignity and monumentality into it, as if it were a mockup for a carving on Mount Rushmore, and see the deep magenta panels flanking the face as an attempt to mix red and blue.

There was at least one instance of art predicting life. At the Nicole Klagsbrun Gallery on West 26th Street, in a show that opened Sept. 8, Nancy Davenport unveiled ''The Apartments,'' a series of simulated photographs made over the last three years that depicted terrorists, alternately sinister and comic, lurking on the roofs and balconies of anonymous New York apartment buildings. (They were actually images of the artist's friends photographed in a studio and then inserted into the pictures of buildings on the computer.)

While convincingly done, before that Tuesday the images would have been little more than a wrinkle in the history of setup photography; until then, they depicted what most Americans considered an impossibility. Now they seem horribly real. Ms. Davenport said she intended the images to be neither humorous nor an explicit warning. But, she said, ''I was aware of the fact that it could happen here, and of the incredible innocence of this country, which I share.'' The artist and her dealer debated whether to take the show down. It is open again.

By far the eeriest, most affecting coincidence can be seen in a show at Postmasters Gallery on West 19th Street. The first show in 10 years by Wolfgang Staehle, a German artist who has lived in New York since 1976, it opened on Sept. 6 and contains three live-feed video projection pieces. The centerpiece is a panoramic view of Lower Manhattan measuring 9 by 22 feet, which is transmitted to the gallery from two cameras facing south from the window of a loft in the Williamsburg section of Brooklyn.

On the Saturday before that Tuesday, it offered a sweeping, postcard-perfect view of the southern third of Manhattan and its skyline and the East River and its bridges, with the twin towers reaching almost to the upper edge of the image. Mr. Staehle had titled the piece ''To the People of New York'' and said he intended it as a kind of contemporary landscape painting, one using the latest technology and showing the world simply as it is, in real time. (The effect is of real time slowed down: the cameras transmit an image every four seconds, so that, for example, boats move up and down the river in short spurts.)
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It was a beautiful awe-inspiring sight, and people entering the gallery on that first Saturday tended to be struck silent by its grandeur, mundanity and simple conjuring of the ceaselessness of time, light and life. In the two other works, time unfolds in other parts of the world with a similar quietude, adding the resonance of simultaneity. One shows a 50-year-old communications tower in the eastern section of Berlin, a tall, gangly structure that looks dark and ominous during the day and turns into a sparkling chandelier-like bauble at night. The other is a 15th-century monastery perched majestically on a hilltop in an area of Germany near Munich where Mr. Staehle grew up. Shortly after 9 a.m. on Sept. 11, Mr. Staehle, who was watching the terrorist attack from the roof of his apartment building on Ludlow Street, called Magda Sawon, the owner of Postmasters, who lives behind the gallery with her family. He told her what was happening and to turn on the Manhattan projection. Ms. Sawon did so, and with her son at school and her husband in Los Angeles, she stood alone in the big darkened gallery and watched the collapse of the buildings, unlike most people, in total silence. The towers came down in real time and chilling slow motion, and what was intended as a form of contemporary landscape painting became a living history painting, a picture of history in the making. Last Saturday, all three projection pieces were still in operation and the people looking at them were more silent than ever. The images of the Berlin tower and the German monastery stood unchanged in the slowly shifting light, offering proof of life going on. The majestic view of Manhattan offered similar proof except that the skyline was different and the sky was newly blank, and Mr. Staehle had changed the name of the work to ''Untitled.''