Post-modern dance pioneer Anna Halprin, who celebrates her 90th birthday in July, is a force of nature. Not the kind that steamrolls everything in its path, but a gently, relentlessly persistent drive, like a wave. Breath Made Visible, Ruedi Gerber’s portrait of the artist as an ageless fount, transports us to the woods of Marin County, where the pioneering dancer and choreographer has lived and taught the principles of improvisation and collaboration for decades. The documentary’s physical center is the enormous wooden deck that the late landscape architect Lawrence Halprin built for his wife, pitched among the redwoods in their vast yard. It serves as studio, performance space, healing hub, refuge, and mecca for those drawn to Anna’s seer-like spirit and grace. It’s no small feat to make a legend life-size and accessible without dispelling her greatness and mystique, yet Gerber pulls off a delicate tightrope act with relaxed ease. Anna Halprin will be at Cinema Village on April 23 and 24 for the 7 and 9 pm screenings.