Research of three dimensional visualization of cylindrical gear based on VTK and Hoops

The involute cylindrical gear modeling was more precisely made by combining the characteristics of VTK and Hoops. By adopting the parametric modeling method, the basic parameters and structual parameters of the gear were conformed. The gear model was divided into three sub models that are tooth model, web model and hub model. The VTK's principles of entity modeling were used to construct those sub models. By deducing the formula of rotational extrusion angle, the precise of helix angle was guaranteed. Through the research of the structure of VTK's polygon data and Hoops' shell data, the transformation between the VTK model and Hoops model was realized. At the same time, the Hoops Boolean operation was applied to joint those sub models together, after that the whole gear model was got and it was displayed by Hoops B-Rep method. The meshing process of the gear pair model in the 3D scene was analyzed and described and the automatic meshing was made to come true.