SOUTH PACIFIC ENTERS THE AGE OF HIGH DEFINITION SATELLITE IMAGERY

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By Patrick Antoine Decloitre

SUVA, Fiji Islands (March 4, 2001 - Oceania Flash/SPC)---Newly introduced high definition satellite images now enable South Pacific island countries and territories to have access to much more affordable, yet reliable research and monitoring tools.

The Pacific's huge area and its scattered locales have always been major challenges for island countries and territories.

But since January 17, things seem to have changed: the South Pacific Applied Geoscience commission (SOPAC), a regional organization that groups 18 countries and territories, has started to work on satellite image data taken by Ikonos 2, a satellite that was launched into space in September 1999.

The development now enables SOPAC's Pacific member countries to have access to a new generation of high resolution data (four meters in color and one meter in black and white) at a scale never obtained before, except by traditional aerial photography.

But aerial photography has always been regarded as expensive. It required hiring a plane and a crew, flown from overseas.

And it had its drawbacks. If it turned out that the aerial pictures were taken on a cloudy day, and were useless, the costs were still levied.

"This (satellite imagery) provides detailed resolution and now allows (us) to replace aerial photography," SOPAC's Wolf Forstreuter, explained.

"Overall, this is definitely cheaper, because with the satellite you only pay for the cloud-free (photographs). You don't have to wait until the flying crew is in the country, (or pay for) the stand-by costs. And the data, once received, is ready to display on a computer."

"Practically, those digital images are immediately available on a computer screen and can be used for interpretation, according to specific needs. . . Power or water utilities specialists can use them to localize their customers, to plan their new connections, for example."

The first satellite image ordered by SOPAC arrived on January 17. It covers Tonga's capital, Nuku‘alofa, with a four-meter resolution.

"This new data provides a new dimension, compared to previous space-borne data. Before, it was only a maximum resolution (on a scale of 1/50,000). Now we're going into a 1/10,000 scale, something only aerial photography could achieve so far. So now we can compare the situation of a coastline, over a ten to twenty year timeframe, because we still have aerial photographs and now we have (new) similar scale images. So what happens is that we can overlay it and compare those different pictures on the same scale.

The four-meter spatial resolution allows identifying single houses and single trees around the houses.

But the collected data is also used to provide further information, called geocoded format.

"This means that the display is not limited to the image; the x and y map co-ordinates can be shown . . . for every point of the image."

"In the case of Tonga, the image data will primarily be used to compare the current situation with coastline documented years ago on aerial photographs, to follow up coastal erosion.

"Secondly the GIS backdrops produced from the images will help utilities, in particular the Tonga Electrical Power Board," SOPAC said in a release.

Since most of the old aerial photographs are at a 10,000th scale, they also become immediately compatible with the new satellite image format, also at 10,000.

"With these images, it is now possible to disseminate information more quickly, through the Internet in a simple .jpg file and to integrate global geographic systems and databases," SOPAC's information technology manager Franck Martin said.

© Copyright Secretariat of the Pacific Community, 2000

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