DALLAS, TX.- Very few artists whose work is discovered after their death manage to break through the consciousness of the art world, let alone popular culture at large. Vivian Maier is one such rarity; her photographs caught the world's attention by 2013, four years after her death and six years after storage locker sales in Chicago that had unearthed thousands of her photos and negatives. The photographs are so instantly compelling and authoritative that the canon of great street photographers who captured on film the 20th century in all its complexities – among them Henri Cartier Bresson, Garry Winogrand and Elliott Erwitt – found itself with a mysterious and fascinating new member, one who had lived and worked as an itinerant nanny and who took photographs far and wide for more than four decades. Maier, who never sought publicity, has since been consistently named as one of the most popular photographers of the last century and one of the most recognized names in the art world.

Her work, and Maier herself, has been the subject of ongoing international museum exhibitions, documentaries, think pieces, and books. (This spring Maier's work is the focus of an exhibition at Fotografiska New York.) While it's estimated that Maier took upwards of 100,000 photos, the vast majority of her work surfaced as negatives; Maier rarely printed her work or had it printed by others. On May 2, Heritage will be the first auction house to present a selection of Maier's photographs that she printed herself or had printed in her lifetime, almost none of which has been made available until now. The event Vivian Maier Photographs: A Singular Vision is a historic one for collectors and followers of her fascinating trajectory.

"This auction is the first of its kind, focused exclusively on Maier and solely offering her vintage work," says Sarahjane Blum, Heritage's Director of Illustration Art. "Offering selections from the collection of Ron Slattery – one of the original collectors responsible for bringing Maier's work into public view – this event features a careful selection of Maier's vintage prints, negatives, transparencies, and personal ephemera. Maier is not thought to have exhibited or sold her work during her lifetime, which makes the breadth of her vintage work available as part of this auction all the more significant."

Among the highlights of the sale are 20 large-format exhibition prints created by Maier in the late 1950s, most of which haven't been made public since their initial storage locker sale. (Though Maier left behind a sizable number of negatives and small proofs, no more than 300 of her large-format prints – ones that she printed or commissioned for print – are thought to exist.) And the fact that she chose these images herself is key, according to Pamela Bannos, the artist, researcher and author who wrote the critically acclaimed book on Maier, Vivian Maier: A Photographer's Life and Afterlife. "These were the photographs that were chosen by her, not for her," says Bannos. "In the case of the enlarged prints, they show her choices and give us a slightly different idea of what she was interested in capturing, perhaps only for herself. This matters because until now collectors have come to know Maier's works through the editors of her posthumous prints and publications."

The selection in this event showcases Maier's unabashed approach to a range of subjects and techniques; it includes intimate and confrontational portraits, an array of beguiling street photography, travel photography, landscapes, experimentation with abstraction, and even expanded narrative. For example, says Blum, "There's a pair of photographs of a beach scene, and in one, two children stand in front of what appears to be beauty pageant contestants in bathing suits. In the second, we see the same bathing beauties, but two older gentlemen are in the same poses in the foreground. It suggests the passage of time. But it also shows how much intentionality she brought not just to each individual shot, but how much intentionally she brought to telling stories through photographs as groupings."

Significantly, the event offers up a selection of Maier's self-portraits – here as negatives and transparencies – in both black and white and in color. These are the pictures took on the sly as she walked through bustling city streets and snapped her own reflection in shop windows and the odd sales-display mirror, and they've proven to be collector favorites. "Compellingly, her ongoing self-portraits showed her seriousness and creativity as a photographer," says Bannos. "And we can see, particularly early on, that she was interested in portraiture – of strangers and otherwise – as tightly framed people represent the bulk of her larger vintage prints." Maier was intrepid, too, as evidenced by her willingness to approach unlikely places and subjects, such as her portraits of down-and-out men on city park benches, and in situ sailors and grave diggers – not the typical company of a lone woman in the middle of the last century.

"There's a broad representation here, which is actually pretty accurate to her entire oeuvre," says Bannos. "Even though we're used to seeing her posthumous images in their native square format, her prints are mostly cropped to fit the paper's aspect ratio. In some of the lots, we can see how she noticed shadows and framing devices and sometimes veered toward abstraction. She also just seemed to be interested in everything around her, as is most evident in her 35mm color photography."

It's that full range of subjects and techniques that distinguishes this collection and shows Maier's evolution as an artist. Through it, her followers can trace her earliest work as it emerged in 1950 during her travels through Europe; Bannos points out that her landscapes are "interspersed with images of a range of subjects, including proto-photojournalist-looking work." In 1952, Maier, an American born in New York to a French mother and Austrian father, began her signature square Rolleiflex work and took her favored tool to the streets of whichever city her employment took her, be it New York, Chicago, and Los Angeles, and on her ongoing travels. Her images show her piercing interest in the daily lives of both children and adults and suggest her awareness of the camera's power to make unfamiliar places and people intimate, and to estrange the familiar. Fiercely private and focused, she did not limit herself in terms of her tools or approaches. "Part of what I learned by studying the various collections of Maier's works was the crossover in materials that showed she used multiple cameras simultaneously," says Bannos. In this event, Maier's work from the 1950s and '60s demonstrates her growing understanding of her subjects and strengths, while unique negatives and transparencies offer a direct connection to the story of Maier's discovery and follow her path in the years after she stopped having work printed.

"There are many ways to get the wrong picture about Vivian Maier," says Bannos. "To get the right picture, look at her squarely, as she would look at you: on her own terms, from her own evidence of who she was and what she did."