Research On 3D Module Structure In GIS

After in-depth studying on integrate approach for structuring three-dimensional spatial geographic object module, the author propose a new approach for designing the three-dimensional module based on object-oriented principle, and use Unified Modeling Language to describe. Meanwhile, in order to speed up constructing the three-dimensional model, the author proposes to split the big module into some small module and parallel building the three-dimensional module based on cloud computation platform.In the paper, the author divides the process into three stages by applying OOP technology, which includes the node design, the face design and the spatial object design. The node object is the atomic object on the spatial geographic object module. The request of the module to the outer factor is responded by the node object finally. However, for man-made attributes also depend on the coordinates of some node object. Because the face object is the most important object being transformed from 2.5- dimensional to three-dimensional, the face object design includes the information of the node for building the face and the tetrahedron building. The most import thing is to form the tetrahedron by the triangle which is also the spatial geographic object. At last, three-dimensional spatial geographic module is integrated by man-made attributes and spatial geographic object.In the paper, the author uses the UML, which is matured in the engineering field, to describe the node object, face object and geometric module. The most important character of UML is that UML doesn't depend on the specific high level programming language. Then, it's no need to consider the character of the programming language while design. So the designers can focus on how to design the module. So, in the paper, the design of all object don't consider how to realize by any high-level programming language.Integration three-dimensional spatial geographic object module includes large number of sampling points which needs the power computing to build the triangle and tetrahedron. So, the author put the three-dimensional spatial geographic object module on the cloud computation platform to compute. By making use of the parallel capability of the cloud computation platform, the three dimension module can be constructed fast. In order to make the better use of the parallel compute of cloud computation platform, author proposes three different types of spatial geographic objects which are the boundary rule space geographic objects, the irregular boundary space geographic objects and the boundary fuzzy spatial objects. Based on different object, author uses different split algorithm to split the completed module into the specific scale modules which are distributed on computing cells of the cloud computation platform to construct the sub three-dimension module. After parallel computing, the full spatial geographic object three-dimension module can be integrated by the sub three-dimension modules.