3d Digital Earth Model Based On Silververlight Build Key Technologies And Applied Research

With the popularity of Windows7 and the blooming of the iPhone, we can sense that people have a certain degree of aesthetic fatigue on the traditional forms program,and have higher demand on the present side. Since the release of Silverlight and Flex, the boom of writing beautiful rich-client Web has beening presented on the Internet. With the popularity of GIS, more and more human production activities rely on map services in the form of static pages. But GIS Web Map Service client display has not made big progress up to now, the traditional 2D map service can hardly catch people's attention, combined with that the operation and resolution of static page mode all depend on the server, and the client machine can not participate in operational role, while Silverlight-based 3D digital earth not only greatly enhanced the display effect on the client machine, but also improved graphic operation ability to a large degree. To GIS mass data which require complex spatial operation ability, compared to the form of static pages, the advantage of rich-client is significant. In view of this, we study the key technology of the construction of Silverlight-based 3D digital earth, including 2D coordinate transformation and graphic operations, the operation of image data, the construction of 3D spherical surface and 2D data projection to 3D surface. This paper has realized the bottom building of 3D digital earth as well as the display of it. This paper's main research work include:1)The current 3D digital earth research mainly is focused on the client side,on the web side there is only 2D map service, the existing literature are rarely involved in creating 3D digital earth, for the rich clients 3D digital earth research is still stay at a theory phase . This article is based on the bottom, involving several suspect of the graphic. This article includes the implement of displaying GIS data on the 3D sphere.2) This article is going to talk about the analysis of the characteristics of image data, designing a flow, which includs the pyramid model for the image data set, extract merge, split, packers and storage and some other operations for managing image data.3)In order to build the 3D environment, it would be necessary to make some research on the 3D coordinate transformation, the key elements that affect the sphere displaying, the error correction of the sphere rotation transform by the last for quaternion.4)After the construction of 3D sphere, this article discussed how to porject the 2D data onto the 3D earth surface, this procedure complete the inverse compute from latitude and longitude to sphere. Further more, this article discussed the method of controlling the point density coordinates of multi-texture and single- texture.5)Finally, developed a system from the bottom that shows the 3D data earth. The system take Visual Studio2010 as the development tool and use the object-oriented approach and is based on Silverlight rich-client rendering technology. The system which combines the spatial database to manage the maintenance of spatial data contains functions like graphical display, multi-image classification, 3D earth panning, the earth rotation and other operations.