Massive transforming robots in 3-D were one of the key selling points in Transformers: Dark of the Moon, and they were a big part of the movie's domestic box office results in the movie's opening weekend.

While distributor Paramount says the total haul domestically over the four-day Fourth of July weekend was estimated to be $116.4 million, 60 percent of that came from the costlier 3D shows, which feature especially equipped theaters that are more expensive than ordinary 2-D screenings.

The film has earned $181.1 million since last Tuesday's opening.

Meanwhile, international sales were $217 million, leading to a nearly $400 million total.

Greg Foster, who heads the IMAX filmed entertainment division, said ahead of the film's release that the movie by director Michael bay showcases visual effects and the director's incredible attention to detail.

IMAX 3D, along with RealD 3D, are two of the leading formats for watching 3D films.

He said advance ticket sales had been very strong.

After James Cameron's Avatar in 2009, 3-D movies are getting their next big test with the latest Transformers film.

Avatar was the most popular and financially successful film in history. It was also made with the 3D movie going experience in mind.

Hollywood has embraced the format with varying results. In an interview last month, Bay and Cameron remarked on the poor quality of some movies converted from 2-D into 3-D.

Bay shot the summer movie with some of the same technology used by Avatar director James Cameron.

3-D was a forethought, not an afterthought in this movie, Bay said in his blog prior to the release.

On the Web:

RealD 3D Theater Locator

IMAX 3D Theater Locator