主题公园的虚拟表述不仅要追求与实际景观的视觉接近，更要描述景观结构、演变以及人地关系等景观的 地理与生态内涵，但后一层次因缺少理论框架而少有研究。基于景观语义特征的虚拟地理环境思想可以很好的 整合两种层次的建模需求。本文以水土保持科技示范园为例，提出了示范园区的虚拟表达对象体系，构建了依据 景观特征语义的园区多细节层次模型(Layer of details, LOD)，较好的表达整体和局部生态景观特征以及微观生态 景观要素的各类语义关系；并且通过不同尺度LOD和景观要素的组合表达，按照不同主题和功能构建虚拟场景和 游览过程模型。研究不仅解决了示范园生态教育普及、科技示范和生态旅游等多功能一体和园区规模、位置、生 态容量等限制之间的矛盾；同时说明基于景观特征语义的LOD模型可以较好地改进传统LOD只注重要素细节的 问题，并能准确表达地理和生态景观意义。多细节层次景观语义模型为虚拟地理环境思想的具体表达提供了方 法学案例，可以方便扩展至其他主题公园、虚拟旅游甚至地理学相关的多种领域。

The virtual expression for theme park, using the virtual reality (VR) technology, has achieved not only for achieving a high degree of realism for every element of the landscape in appearance texture, but also for showing landscape construction, landscape evolution and the man-land relationship and describing the geo-spatial pattern. The latter is paid less attention by researchers. Designing the landscape model based on semantic features in Virtual Geographic Environments (VGE) is a good idea to achieve the two-level modeling, and a case of a water and soil conservation technology park, located in the Yanqing County, Beijing, China, is selected to demonstrate the idea. The water and soil conservation technology park is a special form of theme park, which is designed for the experiments of water and soil conservation technology, popular science education of protection of ecological environment, and leisure and recreation activities. But the park's functions are greatly restricted by the park's area, location and ecological capacity. So it cannot satisfy the multi functional needs for the education of ecological environment protection, technology demonstration and ecotourism development. The authors design a classification system of themes and virtual objects in the water and soil conservation technology park, and build a layer of details (LOD) model for describing the theme park in the computer virtual environment based on semantic context of the ecological landscape. The LOD model can show the features and landscapes of the theme park at different view scales such as the whole view, middle scale view, and some special partial views, even a special feature view in the virtual environment. The LOD model can also construct the virtual environment based on different themes and functions or design a special sight-seeing route by the describing of different scale LOD models and other landscape features together. This case study is done in the ArcGIS 9.2 and the Skyline software platform. The ArcGIS9.2 is used to build the Digital Elevation Model (DEM) of the Park. And the Skyline is a good software for VGE modeling, which is selected to locate the 3D models and express the special semantic contexts. The experiment proves that LOD models based on semantic context of the ecological landscape are better than the traditional LOD models which focus on the details of a single feature in various scale views, and can easily express the multiple functions of scientific research, technology demonstration, popular science education, and leisure and recreation. The virtual expression model can also link easily to various user terminals, especially the Internet, and solve the problems in field trips, such as the restriction of the space, limited ecological and environmental capacity and the low assessibility because of the trip distance. LOD model based on semantic context is an important supplement for theme park developing and a good case of VGE in the tourism researches, especially in the ecotourism researches.