Study On 3D Terrain Construction For Virtual Battlefield

Because every battlefield consists of time and space and the battle units, the construction of virtual 3D terrain becomes a very important component of virtual battlefield environment. How to construct photorealistic and credible virtual 3D terrain becomes more and more important. This thesis focuses on the 3D terrain construction technology and implementation.There are many algorithms in the area of 3D terrain construction which include key technologies as below: digital terrain modeling, simplification technology of terrain modeling, multi-resolution hierarchy terrain modeling and technology of photorealistic rendering. The thesis gives brief summary of these technologies.The thesis proposes a whole set of methods from data collection to 3D terrain scene generating, including data source, data organization, topography data, object data collection, 3D scene generation and rendering. This thesis provides detailed description of these technologies. Further more, it describes several solutions of implement problems and also their features to select appropriate model and algorithm due to application requirements.Secondly, we proposes an improved interpolation algorithm of Delaunay triangulation which enhances the efficiency of LOP(Local Optimization Procedure) algorithm by updating adjacent triangles. Based on the improved algorithm, a Delaunay triangulation algorithm with linear type constraint conditions is implemented.Moreover, we have designed and implemented a system of 3D terrain generation. The thesis gives a brief description of the structures and functions of the system. The logical relation map among the terrain metadata, object metadata, 3D scene data and corresponding export data are also proposed in the thesis.The contribution of our thesis is listed as following:1. A better interpolation algorithm of Delaunay triangulation is proposed by improving traditional LOP algorithm. Lawson's LOP algorithm requires that the new interpolative point be as closer as possible to the barycenter of triangle, so it will optimize the interpolative points table by sorting, and only consider the relation of spatial positions among the interpolated points, the spitted triangle and neighboring ones. Based on the change of the edges induced by the new inserted point, the improved LOP algorithm recursively use Delaunay principle on every triangle which is generated by changing diagonals. It makes an updated procedure from inner to outer. The improved LOP algorithm do not require the interpolative points avoid some special position, even the point on the edge of triangle; it also can function harmonically by diffuse procedure. The improved algorithm is robust and more efficient.2. A Delaunay triangulation algorithm with linear type constraints is proposed.Based on the improved interpolation algorithm of Delaunay triangulation, we add some linear type constraints to construct the Delaunay triangles. This algorithm also works with multiple constraints. By assembling these linear type constraints, we can develop other geometrical constraints. The algorithm is efficient and easy to implement in our applications.