Virtual 3D city models are digital representation of terrain surfaces, sites, buildings, roads, waterways, etc. In general, these models are used for presenting, exploring and analyzing the urban areas. These models are also used in domains of smart city, virtual reality, infrastructure planning, telecommunication, disaster management, real estate services, education, tourism and change detection. There are various approaches and commercial packages to generate virtual 3D city models. In this novel approach, we have not used any commercial package or tool toward generation and visualization of city model but instead developed in-house routines and used libraries from open source domain to generate and visualize real-time virtual 3D city models. Generation of 3D city models involves the imagery from high-resolution satellite, high-resolution digital elevation model (DEM) and vector shape files from open street maps (OSM) (https://www.geofabrik.de/geofabrik/openstreetmap.html) as inputs. Over and above virtual 3D city models, OSM vector layers of road network, river network and important places have been overlaid for making the virtual city model more informative. Toward realism, virtual trees are placed in the open spaces (as per shape file markings), Sun position and day/night effects, ambient condition effects and building texture, has been incorporated. To achieve generation of city model, we mosaicked preprocessed DEM scenes and images, resampled given datasets using cubic-resampling algorithm, registered the image, DEM and vector layers using phase correlation algorithm, and extracted the height information by processing of DEM and shape files. Vector layers are registered using latitude and longitude and overlaid over the 3D city model for information about the places, roads and water bodies. For efficient visualization and rendering of the model, open scene graph library and tiling-based approach are used in which tiles are replaced in the main memory by its sub-tiles based on viewer’s position. Mentioned approach is applicable to generate and visualize city model of any given area provided the DEM, imagery and OSM data. This paper mainly discusses the approach and advantages of this new cost-effective approach to develop virtual 3D city models using Indian Remote Sensing datasets.

中文翻译：

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一种使用开源库生成和可视化虚拟 3D 城市模型的新方法

虚拟 3D 城市模型是地形表面、场地、建筑物、道路、水道等的数字表示。通常，这些模型用于呈现、探索和分析城市区域。这些模型还用于智慧城市、虚拟现实、基础设施规划、电信、灾害管理、房地产服务、教育、旅游和变化检测等领域。有多种方法和商业包来生成虚拟 3D 城市模型。在这种新颖的方法中，我们没有使用任何商业包或工具来生成和可视化城市模型，而是开发了内部例程并使用开源领域的库来生成和可视化实时虚拟 3D 城市模型。3D城市模型的生成涉及高分辨率卫星图像，高分辨率数字高程模型 (DEM) 和来自开放街道地图 (OSM) (https://www.geofabrik.de/geofabrik/openstreetmap.html) 的矢量形状文件作为输入。在虚拟 3D 城市模型之上，叠加了路网、河网和重要地点的 OSM 矢量层，使虚拟城市模型的信息量更大。为了现实主义，虚拟树木被放置在开放空间（根据形状文件标记），太阳位置和日/夜效果，环境条件效果和建筑纹理，已被纳入。为了实现城市模型的生成，我们对预处理的DEM场景和图像进行镶嵌，使用三次重采样算法对给定数据集进行重采样，使用相位相关算法配准图像、DEM和矢量图层，并通过处理DEM和形状文件提取高度信息。矢量层使用纬度和经度进行注册，并覆盖在 3D 城市模型上，以获取有关地点、道路和水体的信息。为了模型的高效可视化和渲染，使用了开放的场景图形库和基于平铺的方法，其中基于查看者的位置，在主内存中的平铺被其子平铺替换。提到的方法适用于生成和可视化任何给定区域的城市模型，提供 DEM、图像和 OSM 数据。本文主要讨论了这种使用印度遥感数据集开发虚拟 3D 城市模型的新方法的方法和优势。使用开放的场景图形库和基于平铺的方法，其中基于查看者的位置将主内存中的平铺替换为其子平铺。提到的方法适用于生成和可视化任何给定区域的城市模型，提供 DEM、图像和 OSM 数据。本文主要讨论了这种使用印度遥感数据集开发虚拟 3D 城市模型的新方法的方法和优势。使用开放的场景图形库和基于平铺的方法，其中基于查看者的位置将主内存中的平铺替换为其子平铺。提到的方法适用于生成和可视化任何给定区域的城市模型，提供 DEM、图像和 OSM 数据。本文主要讨论了这种使用印度遥感数据集开发虚拟 3D 城市模型的新方法的方法和优势。