Ahead of its cinema release, Christopher Nolan famously made a big thing of saying that Oppenheimer didn’t include any CGI. That’s not the same as saying the film doesn’t contain any VFX, and so the matter’s now being clarified.
For the, as has been mentioned here before, pivotal Trinity Test sequence, for example, the VFX team at DNEG, led by Academy Award winner Andrew Jackson layered filmed elements such as smoke and explosions using digital compositing tools and techniques.
“”[Nolan] didn’t want use any CG simulations of a nuclear explosion. He wanted to be in that sort of language of the era of the film … using practical filmed elements to tell that story.”
[The explosion itself was]
“a sort of loose artistic interpretation of the ideas rather than an accurate representation of the physics.”
Andrew Jackson, VFX Supervisor, ‘Oppenheimer’
SFX supervisor Scott Fisher and team filmed a large practical explosion using, according to Andrew Jackson, set fire to four 44 gallon drums of fuel and used high explosives to launch it into the air, plus other elements, with a variety of cameras and lenses, including IMAX and high-speed cameras. In total, a library of roughly 400 individual elements was compiled to create the multiple layers in the compositing process.
“We had some with really close-up detail of the burning explosion. We had a lot of material that we could layer up and build into something that had the appearance of something much bigger.”
[For shots during the explosion sequence]
there were some where there was a [practical] explosion in the background and other ones where we added the explosion. … Some of them had like a lighting effect on the actors for the flash as the explosion went off”
Andrew Jackson, VFX Supervisor, ‘Oppenheimer’
Optical colour timing was used during post production in preference to opting for digital technology. In total,, thethere are about 200 VFX shots in Oppenheimer, including those achieved using practical techniques and those that involved removing modern elements from locations.
Source: The Hollywood Reporter
Andrew Jackson image: fxguide