Enhanced 3D cityscape modeling for enabling the next generation geospatial web

在过去的四年里，地理空间网（GeoWeb）发展非常迅速。GeoWeb是一项强大的技术，它允许人们将各种类型的web内容连接到一个地理位置。有了GeoWeb，非空间的网络信息，如文本、图片、视频、声音等都可以绑定到一个地方。GeoWeb最重要的功能之一是它允许人们在线体验和搜索物理世界。今天，谷歌Earth和微软Virtual Earth等3D GeoWeb浏览器使我们能够通过“飞越”、“驾车穿越”和“步行”探索3D城市景观模型，虚拟地游览全球许多大城市。3D城市景观模型是真实城市世界的虚拟表示，因此是GeoWeb的重要扩展，具有许多潜在的好处。应用包括城市管理、规划和发展；公共安全;环境管理;旅游;电信;交通运输;导航;和电子商务。考虑到潜在的好处，人们对逼真的3D城市景观模型的需求不断增加。然而，目前有效地建立和更新三维城市景观模型的方法是不够的，需要大幅改进。目前的典型方法是利用航空立体图像的立体三维数字化来构建这些模型。这种以手动为中心的方法效率低下，而且对于构建3D地理浏览器中需要使用的大规模3D城市模型来说，这种方法非常耗时。因此，需要新的技术、方法和策略来大大提高大规模使用的3D城市景观模型生成和可视化的速度和准确性。为了应对这些新的重要挑战，本文提出的研究重点是：a)具有高视觉质量的立面纹理的准确和完整的建筑立面三维重建；b)根据细节层次对三维建筑屋顶进行分层重建，实现动态可视化；c)室内外三维建筑模型整合；d)对典型城市环境的树木进行逼真的3D重建。

Over the past four years, the Geospatial Web (GeoWeb) has grown very quickly. The GeoWeb is a powerful technology that allows one to connect various types of web content to a geographic location. With the GeoWeb, non-spatial web information such as text, pictures, videos, sounds, etc.can all be tied to a place. One of the most significant capabilities of the GeoWeb is that it allows one to experience and search the physical world online. Today, 3D GeoWeb browsers such as Google Earth and Microsoft Virtual Earth enables us to virtually travel a number of megacities around the globe with 'fly-through', 'drive-through' and 'walk-through' explorations of 3D cityscape models. 3D cityscape models are virtual representations of the physical urban world and as such are a crucial extension of the GeoWeb that has many potential benefits. Applications include urban management, planning and development; public safety; environmental management; tourism; telecommunications; transportation; navigation; and e-commerce. Given the potential benefits there is an ever increasing demand for photo-realistic 3D cityscape models. However, current methods for efficiently building and updating 3D cityscape models are inadequate and need to be improved dramatically. Today's typical approach is to construct these models using stereo 3D digitization of aerial stereo-images. This manual-centric approach is inefficient and prohibitively time-consuming for building the large-scale 3D city models that are being, and will be, required for use in 3D geobrowsers. Thus, new techniques, methods and strategies are needed to greatly increase the speed and accuracy of 3D cityscape model generation and visualization for use at a massive scale. To address these new and important challenges, the research proposed here focuses on: a) accurate and complete 3D reconstruction of building facades with high visual quality of façade textures; b) hierarchical reconstruction of 3D building rooftops produced according to level-of-detail for dynamic visualization; c) integrating 3D indoor and outdoor building models; and d) photo-realistic 3D reconstruction of trees typical of urban settings.