首先基于集合论方法对体数据内部结构进行分析（内部结构是指被外部物体遮挡或隐藏而不能从外部直接看到的物体或结构），从而给出了内部结构绘制技术的功能要求。基于此功能要求，提出了基于内部结构区域的体绘制技术来分析体数据内部结构的方法。基于内部结构区域的体绘制技术之所以能够分析体数据内部结构是因为该方法把体数据分为两个子集：内部结构区域（或称局部区域）和周围区域。内部结构区域提供了深入体数据内部的机制，通过对内部结构区域的交互，用户可以分析体数据内部的任意区域，从而达到对体数据内部结构和整个体数据的综合理解。该方法还可对内部结构进行量化分析从而提高用户分析体数据的质量。最后，该方法用于分析3维医学图像以显示其在实际应用中的强大功能。实验结果表明，该方法对3维医学图像中的内部结构可以有效地进行定性和定量分析。

In this paper we firstly analyze internal structure（refers to structures that are hidden behind outside structures and can not be seen directly） of volumetric data based on the set theory and describe the requirement for the volume rendering method used for rendering internal structures. Based on the requirements, we propose the use of an internal structure region based volume renderer that offers an alternative for visualization of internal structures of volumetric data. The approach can analyze internal structures because it divides the volume data into two subsets: internal structure region (or local region) and context region. The internal structure region provides mechanisms to peel inside the data set for depicting information of internal structures. The user can analyze and understand any region of internal structures through interacting with the internal structure region. The proposed approach can be used to analyze volume data quantitatively and thus improve the analysis quality. The proposed approach shows powerful usefulness in 3D medical image analysis.The experiments show that the proposed approach is effective for analyzing inner structures.