LOS ANGELES (Hollywood Reporter) - Indiana Jones' return to the big screen after 19 years underscores how much visual effects have evolved.
When the first three Indy films were made in the 1980s, the visual effects were done optically, i.e. photographically or in post-production.
"Indiana Jones and the Kingdom of the Crystal Skull," which topped the North American box office this past weekend, marks the first time sophisticated digital techniques were used in bringing the story of the archaeologist-adventurer to life.
"There were many challenges," said visual effects supervisor Pablo Helman, a veteran of "Indiana Jones" creator George Lucas' effects house Industrial Light + Magic (ILM).
"One was working on a movie that had so many fans and coming up with work that matched the other movies. That was something (director) Steven Spielberg wanted from the beginning."
Helman, a native of Argentina, said he and his team used a wide variety of techniques to make the scenes believable.
"The idea was to be on location as much as possible and then augment (with visual effects) to finish telling the story. ... We always started with principal photography, then we had miniatures, computer-generated elements, practical elements."
The chase in the jungle is an example of how the digital tools were used.
"They shot as much in the jungle as they could," associate visual effects supervisor Marshall Krasser said, adding that the actors were filmed against a blue screen separately.
To complete the shots, ILM created what was essentially a drag-and-drop jungle.
"We had a library of plants and stuff (computer-generated and photographed elements) to drag and drop into position ... We ... dragged vehicles into environments."
The system helped the vehicles interact with the environment, for example, by digging up debris.
"We even added bugs flying around in some of the shots to sell the sense of realism," Krasser added.
The climactic sequence inside the heart of a temple was one of the most challenging.
The movement of the chamber in the scene occurs through a combination of computer-generated imargery and miniatures. For it and other scenes in the film, ILM developed a software application called Fracture that allows the user to break surface objects in a realistic manner.
Lighting was added to enhance the realism of the shots.
"We didn't want the effects to be visible, to overshadow the events that were occurring on the screen," Krasser said. "We've trained an audience of critics."