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Applications of ROCSAT-2 Images in Daily Monitoring
An-Ming Wu, Frank Wu
National Space Program Office
8F, 9 Prosperity 1st Road, Science Park, Hsinchu, Taiwan
Email: amwu@nspo.org.tw,
fwu@nspo.org.tw
Ching-Jyh Shieh
National Science Council
19F, 106 Hoping East Road, Taipei, Taiwan
Email: cshieh@nsc.gov.tw
Abstract
ROCSAT-2 satellite has been launched at UTC 2004.5.20 17:47, and is currently operated on a
14 rev/day circular Sun-synchronous orbit with 891 km altitude and 99.1 deg inclination. The
local solar time of descending node is 9:22 a.m.. The satellite carries the remote sensing
instrument (RSI) for the main mission to daily image over Taiwan and the surrounding areas.
RSI will provide images for 2 m ground sampling distance (GSD) in panchromatic band and 8
m GSD in four multispectral bands. ROCSAT-2 will also daily revisit some areas worldwide
during the 5-year mission lifetime, and will help for the observation of daily variation
phenomena including disaster evaluation, environment monitoring, and vegetation investigation.
RSI utilizes the agility of the satellite bus for stereo imaging over a specific region, continuous
imaging over a slender region, and mosaic imaging over a large region. The imaging
capability is 8 minutes per orbit, and the imaging areas during one cycle can be one 3000 km x
24 km continuous strip, two 100 km x 24 km stereo pairs, four 100 km x 24 km strips, or eight
scenes. The image processing system (IPS) has been implemented to handle imaging
scheduling, data ingestion, data processing, and data management. According to the requests
by the users, IPS performs the imaging scheduling and informs the mission control center to
upload commands and download the telemetries. The signals are ingested and transformed to
the image raw data, which are then processed with radiometric and geometric corrections.
Finally, the image products can be printed, archived, queried, and assessed by the users through
internet. The whole process can be accomplished in 2 hours for the emergency operation.
Since RSI powered on and began to take images on June 4, 2004, ROCSAT-2 has completely
imaged over Taiwan in two months. Some areas are imaged continuously and even
dynamically monitored. Examples include disaster areas, harbors, and airports. ROCSAT-2
satellite will complement the existing imaging satellites like SPOT-5, IKONOS, and QuickBird.
With the unique capability of daily revisit, its applications will have impacts to many aspects in
disaster, environment, agriculture, forestry, education, and international cooperation.
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