Computer-generated gunshots are not as easy they sound

The Washington Post

The Alec Baldwin-involved shooting on the Rust movie set last week that killed cinematographer Halyna Hutchins has had led to a call by some in the TV industry for using only computer-generated gunshots. "But many directors have long preferred the sight of real guns firing, which they believe looks better and keeps viewers more invested in their story," says The Washington Post's Steven Zeitchik. "The technology is now advancing to the point they’d have less reason to resist — but it’s a halting advance. Traditional computer-generated (CG) images, it turns out, can achieve some but not all of the effect of a traditional firearm. One innovation, photogrammetry, can actually replicate the full effect of a real gun, but it’s a more involved and costly process. A real-life gun shot can be broken down into three components: The recoil of the weapon; the muzzle flash (that burst of light from when hot high-pressure gas mixes with air as it exits the gun); and the impact when the projectile at the front of the cartridge hits. Using a live weapon to shoot a blank (i.e., a cartridge without the projectile) is a time-honored Hollywood way to re-create a gunshot. Why not? It perfectly captures the first two parts of the process. The actor is pulling the trigger on a real gun, causing a recoil, and the real gun creates a real muzzle flash; the blank just means there is no bullet at the tip. The third part is taken care of by squibs — micro-explosive charges distributed elsewhere — which are timed to detonate, releasing ketchupy makeup on a shirt or making a hole in a wall. To innovate and try to do this without a live weapon means technology needs to step in. CG can actually create light that looks pretty good. And a gun shot is usually just one or two frames anyway. But in real life a blinding flash does not stay static on the gun — it bathes the whole room and everything in it in light. That’s where the problems start...In other words, a gun in CG can go off, but the light from it does not go anywhere, just stops at the end of the barrel like one of those mini-flags in a clown gun. This is where photogrammetry, an in-screen tool that converts images from two to three dimensions, can help. The tool is pretty new, and many effects houses don’t regularly use it."