How do you think the new GigE standards will influence the machine vision industry?
Respond or ask your question now!
One of my favorite guests on the show is named Rusty Height. He is the self-proclaimed “human crash test dummy.” He agreed to t-bone, or broadside, a moving car for us while driving at 40 miles per hour (Figure 5 – Crash test sequence, three angles). Obviously, this was a one-shot deal and we wanted to make absolutely sure we got as many views of the crash as possible.
For this shoot, we used the Photron MH4 multi-headed camera system. This camera has one processor that we mounted in the trunk and powered from the car’s battery. From the processor we could attach four micro high-speed camera heads. Each camera head is 1.5 inches cubed and provides 2,000 fps in standard definition.
We mounted one camera on the roof, looking out over the hood toward the target car. We mounted two inside the passenger door, looking back at Rusty and one focused on the steering wheel for airbag deployment, and one on the dash board for a face-on look back at Rusty. Since we knew Rusty would have other things on his mind besides remembering to trigger the high-speed cameras, we positioned a pressure-sensitive trigger on the bumper of his car. We set the camera triggers to record four seconds before the impact (trigger) point and four seconds after, to ensure we caught all of the drama of the “run-up” as well as the crash and its aftermath. In addition, we brought in a few extra SA1 cameras including one that we sent up in the basket of a hook-and-ladder fire truck suspended high above the impact site for a true overhead view. When Rusty saw the footage, he made the point that there was a tremendous benefit to having this crucial footage of an actual human being involved in such a crash, as opposed to a dummy. Having the in-car camera footage enabled him to pick out several details that he had never seen before.
THINK INSIDE THE BOX
Everybody loves a good explosion, so we have at least one in every episode. They make for riveting TV and are an ideal subject matter for high-speed cameras. Normally, cameras are positioned at a safe distance with long zoom lenses. But for Time Warp we wanted to give the viewers a true “inside look” at these explosions. But even these ruggedized cameras were not going to survive the blasts from the close proximities from which we wanted to cover them.
Why was it so important to have the cameras as close as possible? What is wrong with a safe distance and a long lens? The answer is depth of field. When you use a long lens and zoom in, you essentially compress your depth of field. When you are right up next to your subject on a wide lens, the whole scene is in focus. If you are close and tight on a wide lens, you get the feeling that you really are inside the explosion as bits of shrapnel, fireballs, and debris whiz past the lens. To achieve this effect, we had to design several blast boxes for the cameras (Figure 6: crew setting up ruggedized blast box). Essentially, we constructed large rectangular housings out of eighth-inch steel. We hinged one side so we could have access to the camera for set-up and focusing. The front panel was half-inch Lexan and we had interchangeable rear panels with and without cooling fans to prevent overheating. On the bottom of our blast box were several mounting options so that we could secure the box to just about anything. In some cases, we mounted the boxes right to the concrete.