Mr. De Maria went to California two months ago to celebrate his mother's 100th birthday and had a stroke there a few days later. He had remained there for treatment. Elizabeth Childress, the director of his studio, said that he died in his sleep, perhaps of a second stroke.
In a career of more than 50 years Mr. De Maria made drawings of all-but-invisible landscapes, gamelike interactive wood sculptures and a record of himself accompanying the sound of crickets on the drums.
Mr. De Maria himself was a sometime percussionist who played in jazz and rock groups in New York in the 1960s, including one that evolved into Lou Reed's Velvet Underground. Yet as an artist in later years he avoided the limelight, rarely giving interviews or letting himself be photographed.
He was best known for large-scale outdoor works that often involved simple if rather extravagant ideas or gestures: a SoHo loft filled with two feet of earth, for example, or a solid brass rod two inches in diameter and one kilometer long driven into the ground in Kassel, Germany, so that only its smooth top was visible (a work consistent with an artist who once noted that "the invisible is real").
In other works Mr. De Maria favored shiny metals and pristine floor-hugging geometric forms that were often repeated in great numbers. Early in his career, he earned the unwavering admiration of a German art dealer, Heiner Friedrich, who went on to become the founding director of the Dia Art Foundation in New York. Dia was dedicated to enabling a handful of mostly Minimalist artists realize ambitious, permanent, pilgrimage-like projects, and Mr. De Maria became one of its leading beneficiaries. The foundation financed four of his best known site-specific pieces and continues to maintain them.
The most famous is "The Lightning Field," which opened in 1977 in western New Mexico after several years of trial-and-error construction. The work is a grid of 400 stainless steel poles averaging 20 ½ feet in height and spaced 220 feet apart covering an area 1 kilometer by 1 mile.
The possibility that lightning would strike the poles was rarely fulfilled, but the piece could look glorious at dawn or sunset, and its hard-won perfection all the points of the poles were at the same level brought a striking sense of order to the desert.
Another work that opened in 1977 was Mr. De Maria's "New York Earth Room," also a Dia project, which consists of a 3,600-square-foot loft at 141 Wooster Street in SoHo filled with 22 inches of dark loamy earth (specially treated so that nothing is supposed to grow in it). The piece, which recreates one the artist first executed in Munich in 1968, exudes a slightly moist, muffling atmosphere and affords a sight so surreally, deliriously startling as to be simultaneously ridiculous and sublime.
The Dia Foundation also made possible "The Vertical Earth Kilometer," another 1977 work, in Kassel, and its 1979 companion piece, "The Broken Kilometer," which consists of 500 two-meter rods of brass arranged in perfect rows on the floor of a ground-level space at 393 West Broadway in SoHo, where it remains on permanent view.
It gave rise to numerous other gallery-sized floor pieces, including "The 2000 Sculpture" (1992), which inaugurated the Resnick Pavilion at the Los Angeles County Museum of Art last fall.
Walter Joseph De Maria was born on Oct. 1, 1935, in Albany, Calif., near Berkeley. His parents were the proprietors of a local restaurant and known for being extremely outgoing. Their son was shy, however, and studied music first piano, then percussion. He also took to sports and cars, of which he made drawings.
By 16 Walter had joined a musicians' union. From 1953 to 1959 he attended the University of California, Berkeley, studying history and painting, the latter under the painter David Park, who was also a musician and had a jazz group in which Mr. De Maria occasionally performed.
During these years Mr. De Maria was part of San Francisco's developing avant-garde scene, participating in "Happenings" and theatrical performances and turning increasingly to three-dimensional works. His friends included the composer La Monte Young (later to become another Dia beneficiary) and the dancer Simone Forti, whose task-oriented choreography made him interested in interactive sculpture. Mr. De Maria moved to New York in 1960 and immersed himself in the downtown scene. He participated in Happenings with Robert Whitman (who was then married to Ms. Forti) and briefly ran a gallery on Great Jones Street with him, exhibiting Minimalist sculptures made of wood.