The most recognizable scene of CGI is the photo shown below of Walker's brother in as a body double and Paul's actual face on the body double.
Viewers who pay careful attention will note that the majority of
Walker’s unfinished scenes are completed using his brothers Caleb and
Cody as doubles. When combined with CGI, carefully chosen camera
angles and the right lighting, they are the spitting image of Paul.
Walker is not the first actor to get temporarily revived through
visual effects. Oliver Reed was digitally recreated for his
unfinished scenes in Gladiator when he passed away during production
and Nancy Marchand had one final scene on The Sopranos after her
death. And then there are the countless commercials that resurrect
iconic celebrities like Steve McQueen and Bruce Lee to hock
Robin Shenfield, CEO of London-headquartered The Mill explains:
Today, it's possible to create an actor entirely from digital
composites. The Mill, for example, has completed a 90-second Johnny
Walker ad featuring a CG Bruce Lee for agency BBH in China. "We
created his entire face in CG and hand-animated that, using shots of
the actor for reference," says Shenfield. He believes that a CG actor
is an option, as long as artists can create his face convincingly.
"The eyes require a lot of work," he says. "Keeping motion continuous
in the musculature and the eyes is the key to making it look real."