With the phenomenal box office achievements of "Finding Nemo" a fading memory, Pixar is attempting to succeed where many studios have failed - with a hit sequel years after the original.
When "Finding Dory," starring Ellen DeGeneres and Idris Elba, comes out in the United States on June 17, a full 13 years will have passed since Marlin the clownfish delighted audiences with his quest to find his disappeared son Nemo. Studio bosses will be aware such a long gap can be a real buzz-kill, with numerous follow-ups to huge blockbusters bombing at the box office because the appetite for their themes and characters faded with time. "Bambi II," which came out 63 years after the original, was a relative failure, while critics said "Fantasia 2000" was a pale imitation of the 1940 film.
Critics resented having to "Return to Neverland" and "Return to Oz" - 49 and 45 years respectively after "Peter Pan" and "The Wizard of Oz" delighted cinemagoers.
More recently, there have been a few successes: "Mad Max: Fury Road," the fourth in the series, put director George Miller center stage during this year's Hollywood awards season, 36 years after the character's first silver screen outing.
Sylvester Stallone, too, loomed large on the nominations lists for his turn in the much-praised latest "Rocky Balboa" instalment, "Creed." But for every "Mad Max" or "Rocky," there is a "Zoolander," "Shaft" or "Tron" which makes the task of following up distant hits look almost impossible.
"Finding Dory," due for its theatrical release on June 17 in the US, is set six months after the events of "Nemo" and follows the travails of Marlin's forgetful companion Dory, a Pacific regal blue tang.
Underwater odyssey
Jeff Bock, a box office expert at statistical website Exhibitor Relations, said love for Nemo had actually grown over the years and he expects "Dory" to take about the same as its predecessor - somewhere in the region of $1 billion.
"It's never too late to introduce a spin-off, sequel or reboot, with one caveat: it had better be an authentic attempt to bolster or maintain the legacy of the source material upon which it is based," added Paul Dergarabedian, an analyst at marketing data company comScore.
"Dory" director Andrew Stanton, who was also behind "Nemo," said Pixar had been clear when they were in negotiations for the buy-out by Disney that they would only make sequels if they had "a story that really holds up."
Stanton's writing credits include all three "Toy Story" movies, with the fourth instalment due out in 2018, and he has directed, produced and voiced numerous Oscar-winning animated films over a 30-year-career.
"Each movie is four years of my life. So I have to ask, do I really want to spend 16 years of my life with fish movies? It really has to be something I want to spend four years on," the 50-year-old said.
The premise underpinning "Dory" - an underwater odyssey to find lost family - is the same that paid off so handsomely for "Nemo."
A crew of almost 250 have been taking the sequel from script to screen via 108,000 pages of storyboard and the conception and animation process for new characters.
Visual universe
A big challenge has been to stay true to Nemo's visual universe while integrating technological advances that have taken place over the last 13 years. As Dory and Marlin meet in "Finding Nemo," the water which surrounds them is invisible and without texture, evident only in the undulations of algae and the movement of the characters' fins. The characters meet again in "Dory," but this time the audience is treated to a marine world of incredible detail featuring tiny plankton, shadows and sunlight on dancing on reefs and algae, air bubbles and displaced sand clouds.
Talk show host DeGeneres reprises her role as Dory, with Elba taking the part of sea lion Fluke in an all-star cast which also includes Diane Keaton and Michael Sheen. As he was working on "Nemo," Stanton was amused by the notion that some fish have memories spanning just five seconds, but he didn't know how to bring this idea to life through his characters. "Then I finally heard Ellen on TV and I heard her change the topic five times in one sentence... then I couldn't stop writing," he told AFP.
Stanton telephoned DeGeneres and said he'd written a character for her and that his film would be ruined if she didn't take the part. "She said: 'OK then, I'd better do it.' And that was it," Stanton recalls.
"That was the shortest conversation. Then the second shortest conversation was on 'Finding Dory.' I told her 'do you want to do it?' and she said 'Yes, done.'"