基于直线平行垂直关系美化三维线框模型

针对计算机线图解释中直线间几何关系可能存在不准确，从而出现视觉 表达问题的不足，研究了基于直线平行垂直关系美化三维线框模型方法。首先，计算正视投 影空间中三维线框模型中棱线方向矢量并选择基准棱线；然后，采用直线间平行垂直约束对 线框模型中出现几何错误的直线进行校正，重新选择已校正棱线为基准棱线重复上述操作； 最后根据新的棱线参数确定三维线框模型顶点新坐标。通过算例结果表明，该方法能够有效 地解决线框模型中出现的平行垂直几何问题，达到线框模型视觉上的美化。

Beautification of Wireframe Model of Three-Dimensional Objects Based onParallel and Vertical Linear Relationship

In order to solve the problem that errors may exist in the geometrical interpretation of the relationship between the lines and thus result in the inadequacy in visual expression, a method is developed on parallel and vertical linear relationship for beautifying the wireframe model of three-dimensional objects. Firstly, the ridge direction vector of the three-dimensional wireframe models in the face projection space is calculated and a benchmark ridge is chosen; then geometric errors appearing in wireframe model are corrected by the parallel and vertical constraint of the linear relationship, the corrected ridge is reselected as the new benchmark and a repeatition of the operation is conducted. Finally, the new coordinates of the vertices of the three-dimensional wireframe models are calculated according to the new ridge parameter. The numerical example shows that the proposed methods can effectively solve the parallel and vertical geometric problems in the wireframe model to beautify the wireframe model.