A big white balloon appeared in New York this week. First on the Lower East Side, then uptown, where 57th Street meets the East River.
The balloon, it turns out, frequently visits the city on business: Its job is to photograph potential views for architects and real estate developers.
“We’ve taken photos from every new skyscraper in the city,” said Curt Westergard, the president of Digital Design and Imaging Service, a company based in Falls Church, Va.
That is, before the buildings were built.
Mr. Westergard’s balloons became popular after Sept. 11, as new laws were enacted that placed more restrictions on urban airspace. It is illegal to fly drones commercially over urban areas, and most commercial helicopters are not allowed to hover at low elevations.
The balloon, which was in New York this week to take pictures at two locations, is 12.5 feet across and travels in a trailer that opens on top, like a jack-in-the-box. When the box opens, a mast guides the balloon, and a winch slowly releases it into the air.
The balloon, one of five of its kind owned by Mr. Westergard’s company, stays tethered to the ground, its height precisely controlled by a laser range finder.