Whether someone's blonde hair is real isn't always easy to tell. But Cornell researchers say faking it in the digital world is a big challenge. Steve Marschner has assisted in the computer-generated effects of movies like Lord of the Rings and King Kong. He says moviegoers can sense when simulations aren't up to snuff.
"If you're rendering, say, blue-haired monsters there's a pretty wide latitude in what the result looks like, and people will accept that it looks like a furry blue monster because they've never really seen one before," says Marschner.
But he says people have higher standards for real virtual people. Current methods for creating realistic digital hair-dos work fine for brunettes, but blondes have always been high maintenance. That's because rays of light not only bounce off blonde hairs, but also through them—resulting in a complicated tangle of calculations that required several days of processing for each frame.
The previous approach, called path-tracing, required the computer to work backward from each pixel of the image, literally tracing each ray of light back to its source.
Marschner's team developed new software that first creates a map of where rays of light travel throughout the hair. This process involves some approximations of the light scattering, but in test renderings the results are nearly identical to the path-tracing approach. And instead of days, it takes just two or three hours to render each frame.
Besides more realistic virtual humans, Marschner thinks this work might even lead to better blondes in the real world by allowing hair care companies to virtually test multiple products.
"You can skip an awful lot of work and you can sort of virtually try out lots of different things and then focus in only on the ones that really work. And so we may well see some improvements in say shampoo formulations that come out of this," says Marschner.
He also hopes to develop better ways to simulate how blonde hair moves, making fake blondes of tomorrow no joke.
Marschner's blonde locks are still a work in progress, but may show up at a theater near you within the next year or two.