On July 4, 1997, the Pathfinder lander touched-down on the surface of Mars exactly where NASA scientists had wanted. The lander module then opened to begin capturing images of the Mars surface and start acquiring valuable data. With hundreds of millions of dollars invested, making sure that the Pathfinder project could gather accurate data was the agency’s primary objective. One of the most effective tools NASA is using in this effort is stereoscopic visualization technology from StereoGraphics, including camera technology, CrystalEyes and Monitor ZScreen.
StereoGraphics CrystalEyes played a role in every step of the mission, including the design of the Sojourner rover, pre-visualizing the landing and surface activities, calculating the size of objects and the distance between them, interpreting geologic information and driving the rover safely on Mars’ treacherous terrain. In addition, StereoGraphics’ Monitor ZScreen was used to analyze and interpret terrain data once the Sojourner rover began exploring the surface.
"CrystalEyes and ZScreen allow our scientists to view the Mars terrain in a natural way and interact with the terrain as if they were really there," said Dr. Daryl Rasmussen, head of the virtual reality group at NASA Ames. "The scientists can act as pilots and explore the Mars surface, take accurate measurements and perform analyses of various features."
Visionary Science
In the development stages of the Pathfinder project, efforts were made to create a surface rover that could traverse difficult terrain. If a vehicle were unable to deal with surface obstacles, or were to become stuck, many of the mission’s objectives would be wasted. Different rover designs were tried, but before expensive prototypes were built, digital models were designed and tested on a simulated Mars surface. In order to fully understand the rover’s capabilities, NASA scientists used CrystalEyes to see what the rover design was capable of and design around potential problems before it was built.
"CrystalEyes lets our scientists see things with natural vision and see how the rover interacts with its surroundings," said Rasmussen.
CrystalEyes’ role did not end with the design and testing of the digital model. Once prototypes were built, NASA created a physical representation of the Mars surface. Equipped with cameras based on StereoGraphics’ design, the rover could relay stereoscopic information to its operators. As the rover moved in its new environment, NASA engineers were able to clearly see what obstacles to avoid and how to maneuver the rover for best positioning to perform its experiments.
For the Pathfinder mission, both the lander and the rover are equipped with stereoscopic cameras based on StereoGraphics’ patented design. These side-by-side stereo cameras approximate human vision and can accurately capture and relay 3D stereo images to scientists on Earth.
By viewing the terrain stereoscopically, shadows aren’t mistaken for deep holes, and the added depth perception helps the operators avoid collisions with rocks or other obstacles. Also, determining how far away objects are form the rover—and from each other—is key to determining which surface objects to analyze. Taking accurate distance measurements is critical to understanding the nature of the object and how it arrived at its current location. And with limited energy resources available, NASA engineers must decide which objects to approach based on how far away they are and weather or not the objects pose a danger to the rover. These things can only be determined with a high enough degree of certainty if the target area is viewed stereoscopically.
Stereoscopic Viewing -
How CrystalEyes and Monitor ZScreen Work
Stereoscopic viewing has long been a useful technique for many professionals dealing with complex, multidimensional data sets. By seeing images in a realistic 3D environment, these professionals can visualize problems and analyze information more quickly and effectively. Common applications for stereoscopic viewing include molecular modeling, mechanical design, mapping, medical imaging and simulation.
The effect of three-dimensionality is a combination of what the human eye sees and the brain process. The distance between human eyes results in each eye seeing an image from a slightly different perspective. The brain interprets information from these two perspectives to create the perception of three dimensions—an effect known as stereopsis.
CrystalEyes and Monitor ZScreen rely on the same stereoscopic principle. The product works with the user’s computer display and software to separate left-eye and right-eye-specific images using liquid crystal shutters. These shutters operate in sequence with the independent left/right-eye views to create the illusion that on-screen objects have depth and presence in three-dimensional space.
An emitter transmits synchronized pulses of infrared signals that are received by CrystalEyes eyewear, which employ liquid crystal shuttering lenses. The lenses continuously transmit separate images to the left and right eyes, creating the illusion that computer- or video-based objects have depth, perspective, and presence in three-dimensional space.
Monitor ZScreen works in a similar fashion. However, instead of employing active shuttering eyewear, the ZScreen is an overlay for workstation displays that alternately polarizes left and right images. The user wears polarized glasses that transmit the correct image to each eye while filtering out the incorrect one. The effect is the same as CrystalEyes and the user sees a crisp, high-definition stereoscopic image.
Alternately displaying left- and right-eye perspectives on a standard workstation monitor solves a major problem of the past—true control of the Z-axis necessary for displaying realistic 3D images. For remote manipulation and viewing of objects, stereo 3D gives the user control, along all axes including the Z-axis, or depth, of changes made to a structure on the screen.
StereoGraphics’ NASA Legacy
CrystalEyes is the same visualization system used by NASA to prototype the original Hubble Telescope fix in 1993 and continues to serve a significant role in enabling NASA scientists to study multi-dimensional data and perform simulations. The product has also been used by Boeing to design advanced aircraft, Ford Motor Company to aid in the engineering of new automobiles, Abbott Labs in its development of the HIV protease inhibitor and General Motors to design safer passive restraint systems.
On July 7, representatives from StereoGraphics were invited to join scientists at NASA Ames Research Center in Mountain View, Calif., to view the final panoramic images being sent from Pathfinder. As part of a very small group to see stereo images as they first arrive from Mars, the StereoGraphics delegation was impressed by the NASA operation.
"It was obvious that using CrystalEyes and ZScreen to view stereoscopic images was an integral part of the mission," said Bob Seltzer, director of marketing and sales for StereoGraphics. "We could see things clearly when viewing stereoscopically that would never have been apparent in a 2D view"
The use of StereoGraphics technology was also a cost-saving element of the project. In order to keep the Pathfinder budget in line with projections, many off-the-shelf technologies were used. The CrystalEyes and ZScreen products used by NASA are the same as those available from StereoGraphics to many industries such as molecular modeling, mechanical design, GIS/Mapping, medical imaging, scientific visualization and many others.
"Using our products probably saved NASA tens of millions of dollars compared to designing and developing their own stereoscopic system," said Lenny Lipton, founder and chief technical officer for StereoGraphics. "NASA recognized early-on that our technology is a superior choice for their purposes and we have been working with them for many years."
As the pathfinder and other projects continue, NASA will be using StereoGraphics
technology to assist their research efforts. Currently, NASA’s Ganimede
satellite is using stereo imaging to map the moon. At the same time, a
next-generation Rover known as Nomad is sending back stereo images from
the Atacama Desert in Chile, testing technology NASA will use on its next
Mars probe.