中文摘要：

地理信息存在于三维空间和时间维中，在多维空间中展示地理信息数据可以从本质上加深对地理现象的认识。太阳在地球表面上的直射点随着时间而变化，本文提出了基于虚拟现实建模语言（VRML），将直射点的变化规律用三维动画加以展示。文中也给出了地平坐标系、大地坐标系和VRML坐标系之间的坐标变换公式，并对建模的关键技术加以了阐述。

英文摘要：

Geographic information exists in 3 D space and time dimension. Displaying geographic information in multi -dimensional en- vironment could help understanding the nature of the geographic phenomenon. The sub - solar point changes over time, this paper pro- posed a method to simulate the sub - solar point in VRML. Formulas of the coordinate transformation are given for horizontal, geodetic and VRML coordinate system, and techniques to build VRML node are also explained.