A documentary on the late Vivian Maier, a nanny whose previously unknown cache of 100,000 photographs earned her a posthumous reputation as one of the most accomplished street photographers.A documentary on the late Vivian Maier, a nanny whose previously unknown cache of 100,000 photographs earned her a posthumous reputation as one of the most accomplished street photographers.A documentary on the late Vivian Maier, a nanny whose previously unknown cache of 100,000 photographs earned her a posthumous reputation as one of the most accomplished street photographers.