NASA /Louise Walker/J.T. Heineck
Now, with a clever six-camera setup, NASA has found a way to see through a rocket launch or other blast. Researchers have built an image-fusing device, nicknamed "Walle," that merges the best parts of images taken by six different cameras. The combined shots offer a superhuman view of even the trickiest high-contrast scenes.
Walle's creators at NASA Ames Research Center built it as a labor of love from spare and outdated parts. Six $35,000 high-speed digital cameras are arranged in a 2 x 3 grid. When Walle starts recording video, one camera properly exposes the dimmest parts of a scene, leaving the brighter parts blown-out white. The next camera takes a shorter exposure, capturing brighter parts of the image the other camera couldn't. The remaining cameras take shorter and shorter exposures until all bright and dark sections are properly exposed.
Where a normal camera can capture only one exposure during a rocket's ascent, Walle's combined images reveal detail in everythingfrom the super-hot fire shooting out of the engines to dark smoke that engulfs a launch pad. "It's a source of data that nobody has currently," says research engineer Louise Walker of NASA's Ames Research Center in Moffett Field, Calif., and one of Walle's co-creators. "If they're not using Walle, they just don't have it."
Each of the six cameras that make up Walle can record a maximum of 4 gigabytes of raw image data, or about 80 to 90 seconds of footage. NASA batch-processes the photos to correct distortion, since each camera records from a slightly different viewpoint. Software then strips out the jet-black and pure-white pixels in each set of six images and fuses the properly exposed portions into one shot.
In its biggest jobs so far, Walle created images of the scorchingly bright plumes belched during the launch of NASA's two final space shuttle missions, STS-134 and STS-135, seen in the images here. But Walle is capable of much more than stunning visuals. It could give scientists views of experiments they've never seen before.
For example, one engineer at NASA's Marshall Spaceflight Center wants to record the super-bright explosions that happen when pressurized tanks rupture, and try to capture chunks of shrapnel that are too dim to be caught by regular cameras as they fly away from a blast. In another project, photographic technologist J.T. Heineck of NASA Ames, who co-created Walle with Walker, plans to record spacecraft materials getting zapped with searing-hot plasma inside an arc jet test (a device used to simulate the heat of atmospheric reentry). "Everything from Mercury to Orion has these materials in heat shields designed to ablate, or heat up and sublimate," Heineck said. With an adapted version of Walle, Heineck says, he could get a better idea of exactly how a spacecraft loses those materials from its heat shield on its blazing-hot return to Earth.
And Walle could have more down-to-Earth applications, too. If software engineers develop real-time image processing for Walle, then, for example, firefighters battling a forest blaze might use it to merge infrared views of the fire with visible-light images of houses, roads and other objects, allowing them to see both views at once.