鉴于传统的图形学-面图形学只能表达三维实体的表面的形状和属性，不能表达实体内部的属性，如纹理、密度场以及温度场等，因而在计算机图形学、CAD以及有限元分析等许多领域都需要一种新的可视化技术-三维实体的可视化技术，以表达实体内部的属性；三维实体的可视化技术是新兴的图形学-体图形学的一个重要组成部分，为了实现三维实体的可视化，针对CAD造型系统中的实际要求，根据体图形学的理论和八叉树的特点，提出了一种基于八叉树的实体内部可视化技术，该技术采用八叉树算法对边界数据结构表达的实体进行体元化。由于实体内部属性变化的不均匀，算法采用了不规则体元，以充分表达实体内部的细节，实际应用效果表明，该算法不但能充分表达实体内部属性，而且也具有一定的造型功能。

The traditional graphics--surface graphics only can display the surface of the 3D objects.It can not display interior properties of the 3D objects, such as texture, density field and temperature field.So many fields such as computer graphics, CAD and finite element analysis, need a new visualization technology for displaying the interior of 3D objects. The visualization technology of 3D object is an important part of a new graphics--volume graphics. Lots of information of solids, such as texture and density, are often hidden in the interior of 3D Objects. Based on the volume graphic theory and the characteristic of octree, this paper proposes a technology for interior visualization of the 3D objects for the demand of CAD system.The octree arithmetic is applied for voxlization which converts geometric objects into a set of voxels that best approximates the continuous object.As a result of uneven changes of interior properties,the technology uses the unequal voxels to best represent the details of interior properties.According to many practices, the technology not only can represent interior properties sufficiently,but also has some modeling functions.