June 2, 2004 EVANSTON, Ill. --- A bowl of blueberries by the thousands, a rock called "Lion Stone," dunes of red sand, the shoreline of a salty sea, wind-sculpted volcanic rock -- all of these features of the Martian landscape come to three-dimensional life for faculty and students when they don their 3-D glasses and step into the Visualization Laboratory at Northwestern University.
Northwestern is believed to be the only university in the country offering its faculty and students the opportunity to view 3-D images of the red planet from NASA's two Mars Exploration Rovers (MER), Spirit and Opportunity, as a component to enhance the classroom experience and for research purposes.
Suzan van der Lee, assistant professor of geological sciences, used the Mars images in her Exploration of the Solar System class to discuss the question of whether or not there was water on the rocky planet.
"Everyone had the funny glasses on in the lab, and we were able to view the same images used by NASA scientists to conclude that there was a shallow, salty sea on the surface of Mars," said van der Lee, who brought 50 undergraduate students to the Vislab in small groups during the winter quarter. "The students were very excited and thought the experience was cool. The 3-D images make Mars more real."
Scientists from Northwestern, the University of Chicago and the Adler Planetarium are bringing these images to the silver screen by taking raw data transmitted daily from the rovers, and, using involved computer programming and processing, turning black-and-white images into full-color 3-D images for academic use.
Northwestern astronomy and geology students, classes visiting from other schools, including Evanston's Roycemore School, and participants in this year's Take Your Daughter to Work Day at Northwestern have all been wowed by the spectacular images. (The 3-D images are also available to visitors to the Adler Planetarium & Astronomy Museum.)
When NASA's Jet Propulsion Laboratory (JPL) launched the rovers last summer, NASA recognized there would be great public interest in the mission. JPL gathered together more than 70 museums and planetariums and formed the Mars Visualization Alliance. The alliance is key in the dissemination of images from the MER mission and in explaining and presenting results of the mission to the public for educational purposes.
"Mars is not that different from an arid place here on Earth, and we can show that to people with these marvelous stereo images," said Douglas Roberts, manager of the Visualization Lab (Vislab) for information technology at Northwestern and an astronomer with the Adler Planetarium. "Most other members of the alliance are using non-stereo images prepared by NASA for the press because they don't have the time to create or the technology to project stereo images."
Roberts arranged for Northwestern to share Mars rover images with the Adler by way of the Visualization Lab and took on the labor-intensive task of manipulating the raw images into a viewable format. Each week Roberts and his colleagues receive data for about 200 images and typically make 50 stereo pictures a week, some in color. (The long-term plan is to create a Web-based library of materials -- of the Mars images and other work with which the Vislab is involved -- to share with other universities.)
As Roberts explains it, the Mars rovers are equipped with camera "eyes" and other sensors that feed them information about their environment. Two panoramic cameras (Pancams) on each rover image the Martian surface and sky. The Pancam Mast Assembly allows the cameras to rotate a full 360 degrees to obtain a panoramic view of the Martian landscape.
The range of filters on the Pancam detectors allows them to take multispectral images (images taken at various wavelengths). Using a "color wheel" with various filters, the two panoramic cameras create stereoscopic images that are later combined to produce 3-D data. Two navigation cameras (Navcams) mounted on each rover's "neck and head" also gather panoramic, 3-D imagery, primarily used to navigate the rover on Mars.
The rovers transmit images to radio telescopes in California, Spain and Australia. Image data is loaded into a database and searched for pairs of images with enough color components for a color stereo pair. Stereo visualization, also known as 3-D visualization or stereoscopy, is based on delivering slightly different images to the left and right eyes. The images appear to have depth as they are projected on a special screen.
Turning raw images into viewable images requires computer programming, plus a geowall system -- a combination of stacked projection technology using polarizing filters/glasses, fast graphics cards and inexpensive PCs which makes it possible to visualize images in stereo and to aid in the understanding of spatial relationships.
Roberts built a computer to display the Mars images and used some moderately priced software for image cropping and alignments. He then mirrored the Adler database and housed it on two servers at Northwestern. The geowall system, which was already in place, consists of a computer containing a graphic card with two video outputs. The computer runs programs such as Pokescope, a stereo program for aligning and viewing stereo photographs, and Wallview, a stereo pair viewer used for very large images.
Stereo images taken through different color filters are combined with Adobe Photoshop (graphics manipulation software) to create stereo color images. NASA scientists often take several overlapping pictures of a large area; these images must be "stitched together" and cropped to form the panoramic images and to fill in any gaps.
Two stacked portable projectors with polarizing filters on their lenses send the images to a silver screen, so called because of the metallic substance on the screen to preserve polarization. Finally (and probably most fun) are the 3-D glasses worn by visitors to the lab, similar to those used at Disneyland or IMAX theaters.
Once he had stereo images that were ready for viewing, Roberts contacted Northwestern's astronomy and geology departments to see if there was interest in using the technology in classes. Not surprisingly, both departments were eager to use the Vislab to supplement their curricula.
Northwestern will have access to the Mars images until the mission ends (currently expected sometime this fall). Roberts is working on stereo images that will be used for future Northwestern classes and as well as disseminated to other universities. As long as there is continued interest in using the images to enhance the classroom experience, the Vislab will continue to offer them.
The Mars expedition also creates enormous opportunities for Northwestern to "take the show on the road." Roberts and Mark Robinson, research associate professor of geological sciences and director of Northwestern's Center of Planetary Sciences, have given a number of presentations at the Adler Planetarium in an effort to do additional outreach and bring Mars even closer to home.
As time-consuming as the Mars project is, there are other projects going on in the Vislab. Work is under way on the 3-D visualization of solid objects such as the Eros 433 asteroid that was visited by the Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft, which sent back images and information about the asteroid for a year. (Eros is an S-class asteroid which means it much larger than a typical asteroid.) Robinson was a project scientist on the imaging team for the NEAR mission.
Work also is being done with Frederic Rasio, associate professor of physics and astronomy, on the visualization of 3-D calculations of dense star clusters and galactic centers.
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