George Ortman, whose constructed, collaged canvases of the late 1950s and early ’60s, with their geometric shapes and signs, pointed a way past Abstract Expressionism and toward the austerities of Minimalism. Mr. Ortman, who was deeply influenced by Surrealism, came of age in the heyday of American abstraction but chafed at the limitations of the flat canvas. He began cutting holes in his canvases and inserting objects wrapped in an aura of mystery. Later, he fitted geometric shapes together in rectangular works that combined elements of painting and sculpture, assemblages that showed an affinity with artists like Robert Rauschenberg and Louise Nevelson.

His interest in signs and symbols led him to incorporate crosses, arrows, diamonds and stars into his work, often deployed in rigorous patterns that anticipated the enumerative impulse in Minimalism.

“I grew up amid Action Painters, and my reaction to all that is symmetry — order in a very strange world,” he told Time magazine in 1964. He added, “People are no longer interested in what Mr. Green says to Mr. Red.”