Filming
Principal photography began on April 25, 2011, in Albuquerque, New Mexico. In June 2011, stuntman Jeremy Fitzgerald injured his head while attempting a stunt involving a 30-foot fall from a building after getting hit by an arrow.
A Marvel spokesperson later told TMZ.com that despite the injury, Fitzgerald recovered and continued working on set. The following month, secondary filming took place about an hour outside Pittsburgh, Pennsylvania in the Butler area.
A chase sequence was also shot in Worthington, Pennsylvania at Creekside Mushroom Farms, the world's largest single-site mushroom farm, which provided 150 miles of abandoned limestone tunnels 300 feet below the ground for filming.
Production relocated to Cleveland, Ohio in August 2011, where filming transpired over a period of four weeks. The city's East 9th Street was chosen as a double for New York City's 42nd Street to be used in climactic battle scenes.
Army Reserve soldiers assigned to the Columbus, Ohio-based 391st Military Police Battalion provided background action during the battle scenes in Cleveland.
Staff Sergeant Michael T. Landis stated the use of real soldiers made the scenes more realistic and helped portray the military in a more positive light, explaining that, "It's easy for us to make on-the-spot corrections to tactics and uniforms, the director actually took our recommendation on one scene and let us all engage the enemy as opposed to only the gunners in the trucks engaging".
A series of explosions were filmed at the Chevrolet powertrain plant in Parma, Ohio as part of the battle sequence that began in Cleveland. Scenes from the film were also shot on Public Square and the Detroit�Superior Bridge.
Filming also took place in the large vacuum chamber at the NASA Plum Brook Station near Sandusky, Ohio. The station's Space Power Facility was used to portray a S.H.I.E.L.D. research facility.
Public Square's southwest quadrant was turned into Stuttgart, Germany, for filming. Principal photography concluded in New York City, where filming occurred over two days. Filming locations in New York City included Park Avenue and Central Park.
For scenes taking place in Manhattan, visual effects supervisor Jake Morrison shot aerial footage for over three days to use as background plates, elaborating that his main objective was to "get as much aerial work in as possible for the audience to see the big expanses, the wide establishing shots, while also making sure that the effects work doesn't look too computer generated".
"We're getting much better at making entirely computer generated environ- ments," Morrison explained, "but there is no substitute for starting with a real image and adding what you need."
Cinematographer Seamus McGarvey stated that he composed the frame with an 1.85:1 aspect ratio to cope with the varying heights of the main characters, explaining that "shooting 1.85:1 is kind of unusual for an epic film like this, but we needed the height in the screen to be able to frame in all the characters like Hulk, Captain America and Black Widow, who is much smaller.
We had to give them all precedence and width within the frame. Also, Joss Whedon knew the final battle sequence was going to be this extravaganza in Manhattan, so the height and vertical scale of the buildings was going to be really important."
The film was McGarvey's first venture shooting with a digital camera, the Arri Alexa. The Canon EOS 5D Mark II and Canon EOS 7D digital SLR cameras were used for some shots, and high-speed shots were captured on 35 mm film with the Arriflex 435.
About his visual approach, McGarvey remarked, "Joss and I were keen on having a very visceral and naturalistic quality to the image. We wanted this to feel immersive and did not want a 'comic book look' that might distance an audience with the engagement of the film.
We moved the camera a lot on Steadicam, cranes and on dollies to create kinetic images; and we chose angles that were dramatic, like low angles for heroic imagery."
Post-production
In December 2011, Disney announced that the film would be converted to 3D. Said Whedon, "I'm not a big fan of extreme long lens, talky movies � I like to see the space I'm in and relate to it, so 3D kinda fits my aesthetic anyway.
And the technology has advanced so far in the past couple years." Whedon also said that "there definitely are movies that shouldn't be in 3D" but "The Avengers isn't obnoxiously 3D.
There's no, 'Oh look, we're going to spend 20 minutes going through this tunnel because it's in 3D!' And no one is pointing at the screen the entire time. But it's an action movie. Things tend to hurtle toward the screen anyway".
In January 2012, it was reported that the film would be digitally remastered for IMAX 3D and open in IMAX theaters on May 4, 2012, the same day it opens in regular theaters. The film's IMAX release follows Marvel's IMAX releases of Iron Man 2 and Thor.
In a May 2012 interview, Whedon said that it was his decision to include Thanos in a post-credits scene, although the character is not identified in the film. "He for me is the most powerful and fascinating Marvel villain.
He's the great grand daddy of the badasses and he's in love with Death and I just think that's so cute. For me, the greatest Avengers [comic book] was Avengers Annual #7 (1977) that Jim Starlin did followed by Marvel Two-in-One Annual #2 (1977) that contained the death of Adam Warlock.
Those were some of the most important texts and I think underrated milestones in Marvel history and Thanos is all over that, so somebody had to be in control and had to be behind Loki's work and I was like 'It's got to be Thanos.'
And they said 'Okay' and I'm like 'Oh my God!'" An additional coda involving the Avengers eating shawarma was shot on April 12, 2012, a day after the world premiere. Shawarma sales in Los Angeles, St. Louis, and Boston reportedly skyrocketed in the days following the film's release.
The film contains more than 2,200 visual effects shots completed by 14 companies: Industrial Light & Magic (ILM), Weta Digital, Scanline VFX, Hydraulx, Fuel VFX, Evil Eye Pictures, Luma Pictures, Cantina Creative, Trixter, Modus FX, Whiskytree, Digital Domain, The Third Floor and Method Design.
ILM was the lead vendor and shared responsibility for creating many of the film's key effects, including the Helicarrier, the New York cityscape, digital body doubles, Iron Man and the Hulk.
To create the on-screen Hulk, Ruffalo performed in a motion-capture suit on set with the other actors while four motion-capture HD cameras (two full body, two focused on his face) captured his face and body movements.
Jeff White, ILM's visual effects supervisor, said, "We really wanted to utilize everything we've developed the last 10 years and make it a pretty spectacular Hulk. One of the great design decisions was to incorporate Mark Ruffalo into the look of him.
So, much of Hulk is based on Ruffalo and his performance, not only in motion capture and on set, but down to his eyes, his teeth, and his tongue." ILM digitally recreated the vast majority of the New York cityscape used in the film.
In total, ILM artists rendered an area of about ten city blocks by about four city blocks. To do this, ILM sent out a team of four photographers to take pictures of the area in a shoot that lasted 8 weeks.
Disney and Sony Pictures agreed for OsCorp Tower from The Amazing Spider-Man to be included in the film, but the idea was dropped because much of the skyline had already been completed. Weta Digital took over duties for animating Iron Man during the forest duel from ILM. Guy Williams, Weta's visual effects supervisor, said, "We shared assets back and forth with ILM, but our pipelines are unique and it's hard for other assets to plug into it. But in this case, we got their models and we had to redo the texture spaces because the way we texture maps is different."
 Williams said the most difficult part was re-creating Iron Man's reflective metal surfaces. Scanline VFX completed the reveal shots of the Helicarrier, from the moment Black Widow and Captain America arrive on the carrier deck to the point where it lifts off. Evil Eye Pictures composited digital backgrounds into shots filmed against a greenscreen for scenes taking place inside the Helicarrier.
 Colin Strause of Hydraulx said, "We did the opening ten minutes of the movie, other than the opening set-up in space" including Loki's arrival on Earth and subsequent escape from the S.H.I.E.L.D. base. Luma Pictures worked on shots featuring the Helicarrier's bridge and incorporated the graphic monitor displays that were developed by Cantina Creative. Fuel VFX completed shots taking place in and around Tony Stark's penthouse at Stark Tower.
Resources: scribd.com, imdb.com,
Wikipedia.org, bluscreens.net | 
