Thalasar Ventures

Globe-imaging software Google Earth has become a cult web product since its release in June last year. By using the Web-based tool, users can fly around the globe and zoom in on the natural features and whole worlds of information added by other users. Google combines satellite images taken by its partners with more traditional aerial photography and sews in a giant “virtual texture, covering the entire globe. The photograph used in this” base layer “varies. But how is it possible for you to zoom from space to a point somewhere above the roof of your house without your computer to a grinding halt? Do you feel the same?

The biggest obstacle to a convincing three-dimensional skydive is data transfer. If someone does not download from the Internet to a meter resolution image of the whole world would take 69 years to 10 megabits per second Internet connection, and 12,400 years a standard 56K modem. Catalog is regularly updated as new satellites suppliers or online, but can be one of the three years before the image is processed and added to the basic level. A little ‘smart about how this image is mapped on a virtual globe on your computer. Exploring the Earth is not little.

So how does Google Earth to dominate it? The software giant will make multi-terabyte base layer structure and using a function derived from the MIP-mapping, stream, only the main parts of the computer. Mip-mapping was raised in the early days of 3D graphics as a way to save bandwidth and processing power in the process of real time rendering. When you see an area of ​​MIP-map closely you can see the texture in all its glory in high resolution. However, as that surface recedes into the distance, the process swaps out the texture for fewer detailed variants, saving the graphics card from drawing a texture you wouldn’t see properly anyway.

Google Earth does something similar, using a stack of MIP-maps representing the earth’s surface as seen at different distances, and draw a narrow column of that cell at any time. Around the midpoint of the window, you get the texture resolution when zooming, but without the heart, it cleverly uses low-resolution MIP-map in a way that balances image quality and performance. This ensures that the most useful level of detail are sent to the graphics card at all times. KML Google can integrate data from their research databases themselves, but also allow others to work with their own databases or online content. As KML is not a huge leap for those accustomed to working with XML, but also allows advanced users to use Google Earth as a basis for their own geographic information systems, applications, or mashups.

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