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Satellite Remote Sensing for the 2002 Winter Olympic Games (continued)

The Solution

A relatively new satellite to acquire high-resolution imagery was selected as the most flexible tool. Space Imaging, Inc., had successfully launched the world's first commercial high-resolution satellite in September 1999. Known as IKONOS, this satellite has the capability to image roughly township-size areas, approximately 11 by 11 kilometers, at 1-meter spatial resolution in black-and-white, and 4-meter resolution in color. RSAC had prior experience with IKONOS imagery and had used the products for various natural resource applications. One 11-by-11-kilometer digital scene costs about $3,500.

One advantage of a stable space-based platform is its ability to produce a geo-corrected image product. Space Imaging claims a 12-meter geolocation accuracy for horizontal distances and a 10-meter accuracy for vertical distances, both without ground control. These are specified as 90 percent circular error for horizontal distances (CE90) and 90 percent linear error for vertical distances (LE90). This means that 90 percent of all measured horizontal points should be within 12 meters of their true location on the Earth. This level of accuracy was important to our intent of using digital elevation models (DEMs) to create a 3-D rendition of the ski area. Unless correlation of the imagery to the elevation data was good, features would not appear as correct.

Traveling at a velocity of 4 miles per second, and at an altitude of 423 miles above the Earth, the IKONOS satellite captured our image of Snowbasin on the morning of August 28, 2001 (figure 1). The image showed the new construction around the base facilities at Snowbasin and did a good job of accentuating the new asphalt concrete (AC) pavement forming the bus turning loop. This was a newly constructed area directly related to the 2002 Olympics that would enable spectators to pass through security before boarding buses at a distant location. Spectators could disembark from these "secured" buses without the need to pass through security clearance again.

Figure 1—IKONOS satellite image
of Snowbasin base facilities.

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