Kim Ballard, Computer Engineer, Electrical Design Branch
- Monday, 18 December 2006
NASA's Kennedy Space Center, FL
Engineers at Kennedy Space Center (KSC) developed the Laser Scaling and Measurement Device for Photographic Images – a camera attachment that uses laser technology – to assist scientists in determining the exact scale of any damages to the Space Shuttle’s external tank when viewing photographs of the spacecraft on its launch pad. This NASA-developed camera accessory also is being used to "shoot" photos that can precisely measure details of crime scenes. When a picture is taken with the instrument, the image is loaded onto a computer and items are then viewable and measurable on the computer screen. Kim Ballard designed the Microsoft-Word compatible software for the device.
NASA Tech Briefs: What is the Laser Scaling and Measurement Device for Photographic Images?
Kim Ballard: The device was invented by NASA senior scientist Dr. Robert Youngquist and uses two parallel laser beams that are an inch apart that create a reference point in a photo. The known distance that these laser beams project can be used to scale anything else in the picture to that reference. The device [a half-pound black box powered by a single battery] screws to the bottom of a camera and when a picture is taken, the beams are projected into the image. The image is then loaded onto a PC and the reference points in the image can be used to measure any anomalies in the field of view or to simply take measurements. It provides the ability for someone to look at photographs and better understand how big or small objects in the photo really are.
NTB: How does NASA use the device?
Ballard: A problem that was noted with respect to the Space Shuttle was that the access platforms, which are a few hundred feet off the ground, used to access the external tank of the shuttle while it is on the launch pad are removed from the external tank itself. You can’t actually get up to the tank physically to inspect holes that may be caused by hail or by birds pecking at the foam that insulates the tank. Since you have to stay about 50 feet away from the actual tank on these platforms, which are mounted on the launch service structures, you can’t physically use a ruler to measure how big some of these holes may be; however, you can photograph these anomalous areas. The technology helps to determine the exact scale of any damages to the Space Shuttle’s external tank by viewing the photographs.
NTB: What is unique about the software?
Ballard: The software is not tied to the instrument directly. It uses anything in a photo that can be used for reference. For instance, if you have a series of screws and you know the distance between the screw heads, you could use those as a visual reference. Once the software knows a reference point – i.e., how many pixels equal an inch – anything can be measured.
The user would first load the image and set up a reference. For example, if the laser spots were known to be one inch apart, that information would be entered into a dialogue window. Markers are then placed on these visual points so the software can calculate how many pixels equal that distance. Instead of using a root mean squared, I used an averaging formula where each hypotenuse (distance) is averaged. The measuring can begin after at least two points have been visually referenced in the software.
NTB: How are law enforcement agencies using the technology?
Ballard: First, after Dr. Youngquist presented the prototype, Armor Holdings [a Jacksonville, Florida-based manufacturer of crime scene investigation accessories] got involved and made their “little black box” and commercialized it. Dr. Youngquist asked me to write the software to support the consumer end of it.
When digital photos are taken of a crime scene, a reference (in most cases a ruler) is placed in the shot. For example, a ruler would be placed next to a blood spot in order to be able to take measurements. The image is printed on paper and the blood spot is physically measured from the printed document using the ruler as a reference. With the device and software, the cycle is sped up. The ruler is no longer needed and the photograph does not have to be printed.
NTB: You were asked by the FBI to add more capabilities to the software. What were some of the further capabilities they needed?
Ballard: The last release of the software that I completed included the requests from the FBI. They said that while the original release was great, they sometimes had blood splatter that was across a wall. When you have to step back (or zoom out) to take a photograph, you no longer have the detailed resolution to measure minute areas. I enabled them to zoom in and out of the photo, and be able to place a reference point close in or far out. For example, if they wanted to use the one-inch laser dots as a reference, which could not be seen while standing 20 feet back from the wall of blood splatter, they could zoom in and log those reference points in the software. They can then step back and measure the whole width of the blood splatter across the wall.
The FBI had some image file types that they wanted to be included in the software in addition to the ones that were already used: Bitmap, JPEG, Ping, and TIFF. Armor Holdings also wanted the metric added in for their European customers. So I put in inches, feet, miles, yards, and also millimeters, centimeters, kilometers.
NTB: Is the technology useful in other types of commercial applications?
Ballard: Any application that might use digital photography would be able to use the software. Aerial photography and real estate would be two such examples. The technology can be used for measurement purposes in any industry where taking photos is part of the process.