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LABORATORY OF REMOTE SENSING

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OPTICAL IMAGES

IKONOS – 2 Satellite images

The IKONOS 2 satellite launched in September 1999 is the world's first commercial satellite, offering high-resolution imagery. The IKONOS sensor suite is capable of generating 1-m panchromatic and 4-m multi-band images with off-nadir viewing up to 60º in any azimuth for a better revisit rate and stereo capabilities. IKONOS orbits the Earth once every 98 minutes at an altitude of approximately 680 kilometers. It constitutes a sun-synchronous orbit, and therefore the satellite will pass over a given longitude at about the same local time every day. This procedure allows relatively constant shadow angles on subsequent image collections, helping to determine object’s height and radiometric qualities of the image scene. In addition, by collecting 11-bit data it generates images with a high dynamic range of 2,048 grey levels and yields a wealth of contrast information and shadow detail.

The corrected satellite images can be used as navigational tools for various environmental studies. To monitor volcanic activity after the seismic crisis during 1996 – 1997 in Nisyros Island, located at the SE part of the Hellenic Volcanic Arc, optical data from IKONOS 2 satellite were used. This study was conducted within the framework of the European Research Project GEOWARN (IST 1999 – 12310).

The Panchromatic Sharpening Image IKONOS 2 with one meter resolution, for the Nisyros Island (Greece) was orthorectified to produce the Ortho-IKONOS 2 Image.

For the ortho-rectification of IKONOS a Digital Elevation Model (cell size: 2 m) was used as well as 38 selected ground control points (GCPs) offering high accuracy. The latter were measured in (x,y,z) applying Geodetic GPS receivers. An object to pixel space transformation using the ground control points was computed using the polynomial mapping functions of Kratky. An ortho-rectified image was produced with further processing in the Hellenic Geodetic Reference System 1987 (HGRS’87). This image will serve as a basic feature for a multi-disciplinary study relating to Emergency Planning of Nisyros Volcano.

Panchromatic Sharpened image IKONOS 2 of Nisyros Island:

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Figure 1 (600x600 jpg, 117 Kb)

Panchromatic Sharpened Image IKONOS 2 of Nisyros:

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Figure 2 (600x467 jpg, 46 Kb)

REFERENCES:
http://www.geowarn.ethz.ch

Vassilopoulou, S., Hurni, L., Dietrich, V., Baltsavias, M., Pateraki, M., Lagios, E.,Parcharidis, Is. (2002): Ortho-Photo Generation using IKONOS-2 Imagery and High Resolution DEM: A Case Study on Monitoring the Volcanic Hazard on Nissyros Island (Greece), ISPRS Journal of Photogrammetry and Remote Sensing, 57, 24-38.

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