Senin, 26 Mei 2008

Sensor Spotlight: WorldView-1

WorldView-1 is a satellite sensor that was launched in September 2007. Built for DigitalGlobe by another Colorado-based company called Ball Aerospace & Technologies Corp, the satellite is in orbit at an altitude of 496 kilometers. There's a great gallery of the construction of the satellite here.

There is a specification sheet on the DG website that highlights the features and benefits of the sensor. WorldView-1 is a panchromatic sensor that features a 0.5 meters GSD at nadir and 0.59 meters at 25 degrees off-nadir. This makes it one of the highest resolution commercial remote sensing satellites on the market today. See a gallery of imagery here.

Imagery can be purchased at various levels of processing. These include:

Basic: the imagery is provided with a camera model and radiometric/internal geometry distortions are removed.
Standard: georeferenced imagery (but not orthorectified).
Orthorectified: 0.5 meter panchromatic orthos.
Basic Stereo Pair: the imagery has orientation information that allows for 3D content generation in a photogrammetric system.

These products give consumers a lot of freedom in determining the best solution for them. For example, if you want complete control over all the photogrammetric processing, then the Basic product will be the best choice. For GIS users that want an imagery backdrop for their application, the orthorectified product is a good option. For users that don't have any ground control (for triangulation) but still want to extract 3D information in a photogrammetric system, the Basic Stereo Pair is a good solution. This option is also good for remote areas where collecting ground control is difficult, expensive or dangerous.

We added support for WorldView-1 data in the LPS 9.2 release, which will support all the products mentioned above. Specifically, you could use LPS to triangulate the imagery, adjust the radiometry, extract and edit terrain, extract 3D features, create orthophotos, and create final image mosaics.

Lastly, for more information on satellite photogrammetry check out this article in the Earth Imaging Journal. It is written with IKONOS imagery as the example but is applicable for Worldview-1 data processing as well.

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