Geography 2.0: Virtual Globes

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Friday, June 16, 2006

NASA World Wind: from visualization to mission operations tool

Last Wednesday, Patrick Hogan, Project Manager of NASA World Wind, spoke at Where 2.0 in San Jose. Hogan's fifteen-minute talk was a straightforward description of the software, including comments on its open-source nature, Earth and planetary visualization functionality, and ongoing data import development. As Hogan spoke, World Wind Designer Randy Kim demonstrated and drove the software. The most newsworthy item was that World Wind has had 20 million downloads; SourceForge numbers for World Wind list over 7.5 million in the past year.

After the talk, I met NASA's Frank Kuehnel, Randy Kim, and Patrick Hogan. During the conversation, I asked about a few details of World Wind's architecture. First, while World Wind previously represented Earth as a sphere, Kuehnel said that the next version, due this fall, will be an ellipsoid. The team also has been working on a more flexible tiling structure, using polyhedral segmentation. World Wind tiles currently are composed of four-sided polygons. A major issue has been that these tiles become pinched near the poles. As the four-sided polygons approach the poles, the tiles effectively become triangles, causing awkward image texture distortions. With the large number of converging polygons, it also means that the geometry for the poles is quite complex. Kuehnel said the complex geometry and distortions are less problematic for Earth, since the poles are sparsely populated, but that they pose a larger problem for other bodies. Undoubtedly, he was referring to the fact that much of science on Mars and other planets involves research near poles. World Wind's upcoming architecture changes will minimize polar complexity and also allow the mapping of nonspherical bodies--like asteroids and comets.

Other news:
  • Also Wednesday at Where 2.0, Mark Lucas talked about OSSIM, a C++ open-source "high performance software system for remote sensing, image processing, geographical information systems and photogrammetry." As his closing slide, Lucas mentioned OSSIM's virtual globe, osgPlanet. has a page describing this virtual globe, including screenshots.
  • As pointed out on Ogle Earth, Skyline Globe is not yet available for download. Both the website and a SkylineGlobe developer said the download will be available "shortly."

Image: A NASA World Wind 1.3.5 screenshot of the moon's southern pole.