Magic Morphing: Setting Freeze Frames into Motion (page 2)

Like Wild Fire

Other people were discovering similar ideas in the United States. In 1994, Dayton Taylor created a prototype of a camera called the Timetrack. It owed another debt to Kodak, who supplied 60 of their Funsaver cameras. Taylor's apparatus snapped multiple freeze-frames on a continuous roll of film threaded through all 60 cameras.

Around the same time in France, a director named Emmanuel Carlier shot with an array of 50 cameras. Also in France, director Michel Gondry shot commercials and music videos that showcased the effect. It was Gondry's Smirnoff ad that stopped a bullet in mid-flight and led to the new term "bullet-time."

And then came the recent Gap ad. Stopping a jitterbug in mid-air caught everyone's attention. There was no turning back.

The Matrix

The ante was upped considerably in the movie The Matrix.

The director wanted to emulate the fantastic, flying kung-fu moves seen in comic books. Time-slicing was the obvious choice, but involved a big problem: it was necessary to shoot the carefully choreographed scenes against a blue-screen. How in the world would they possibly match the movement to the background plate?

Computing power came to the rescue. The special-effects team photographed every part of the interior and fed the stills into the computer. By stitching and stretching the images, it textured the 3D virtual world to look just like the real thing.

The environment ensured, the cameras were arranged to match the motion. Once again, the computer came to the rescue. With a 3D model standing in for the star, Keanu Reeves, the computer calculated the exact positions required for each camera in the shot. Positioned accordingly, the cameras were aimed with laser guides onto a target in the center of the stage. Then Reeves suited up and hung by wires to do the fight scene against his movie opponent.

For each take, both the beginning and ending cameras in the array were started. For the freeze-frame, the still cameras all flashed in sequence. By sequencing the cameras, they could perform slow motion as well as freeze-frame. The shots were color corrected and stabilized and extra, in-between frames were added to smooth the motion. Finally, the computer-generated backgrounds were rendered and composited with the foreground. The result was hyper-real.

Now you know the secrets behind one of the most technology-intensive special effects of all time. Obviously, this isn't an amateur project. But before you despair, keep reading you can do some very cool bullet-time shots on your home PC.

Bullet-time at Home

You don't need a million-dollar budget to create this cool effect. While it may not look quite like the big-dollar effects you are used to seeing on television, you can pull off a nifty looking effect with a little ingenuity.

To start, set up several camcorders in a semicircle, point them at a central subject and roll tape on all of them simultaneously (see Figure 1). While the cameras roll take a flash photograph of your subject as he jumps into the air. Next import a few seconds of footage from each camcorder to your nonlinear editor and identify the same frame on each tape using the camera's flash as an indicator. Export each frame as a still and then re-import them, placing them on the editing timeline in sequence. Stretch each still frame to three or four frames to extend the duration of the effect. Because there are 30 frames in every second of video, a shoot using 10 camcorders to produce 10 stills, each set to three frames on your timeline, would result in a one-second effect.

To make the effect more fluid you'll need some morphing software. Michel Gondry used this technique to great effect in his excellent music video Like a Rolling Stone in 1995. Basically, there just wasn't enough money in the budget for a multi-camera rig, so he opted to use the morphing trick. You should try it too! Elastic Reality is a perfect choice for this, but other programs are available. Basically, you're going to morph each shot into the next by correlating similar objects in the two images.

When you play your project back, you should get an excellent bullet-time shot, usually with a little artistic warping thrown in to boot.