Research On3D Graphic Modeling For Hydraulic Engineering

In the present hydropower engineering construction, AutoCAD is often used forplanar drawing and design in the design phase. The3D picture is usually shown bytwo-dimensional topographic maps, blueprints etc. But the construction of hydropowerengineering is often located in areas with complex geological structures, and it is notintuitive enough to show the areas with two-dimensional graphics. The surfacetopography of geological body and the space changes of the geology stratification, faultand drape can not be shown excellently. Therefore, three-dimensional modeling is verynecessary, and3d geological modeling is more advantageous to the observation,analysis and research.3D modeling can be used not only in the geological analysis but also in the designof hydraulic engineering. The3D model of the hydraulic engineering can be directlydesigned on the3D geological model. After the3D models of the geologic body andhydraulic engineering were designed and set up, the models can be automatic mesheddirectly, then carries on the numerical analysis. According to the results of the analysis,we can modify the model, then carries on the above steps until the models meet therequirements. The integration of design and analysis is realized.There are many methods for3D modeling system, including boundaryrepresentation which is used most widely. The3D design and analysis system ofhydraulic engineering adopts the boundary representation. The half-edge structure isused to describe the topology information and geometry information of3D objectsseparately. The topology class used to represent the topology includes Model, Group,Solid, Face, Loop, Edge, HalfEdge, Vertex, etc. The geometry class used to representgeometric information includes Surface, Curve, etc. Surface and Curve are both baseclass.In the process of3D modeling and model analysis, all sorts of complicatedcalculations are based on the basic geometry algorithm. The algorithms for point-curvedistance, point-surface distance have been finished based on geometry class. Based onthem and the algorithm for point-plane distance, the algorithms for curve-planeintersection, curve-surface intersection, plane-surface intersection, and the algorithm using multi-level search for surface-surface intersection are also finished.The set operation algorithms including split algorithm, Boolean operationalgorithm, glue algorithm are finished on the basis of geometrical intersection algorithm.They lay a foundation for3D modeling and analysis.The move algorithm is used when3D objects move. It is not only is a change ofcoordinates. The curve and surface, and their condition with Face and HalfEdge are alltaken into consideration.The3D model construction is introduced with the sample of the geological body.The geological stratification, fault and sliding are all considered in the process ofestablishing geological body. Finally the parametric design of earth-rock dam is realized.There are several examples to show the integration of design and analysis for dam andgeological body.