Application of Three-dimensional GIS analysis and operation functions

The current application of 3D GIS is mainly limited to 3D visualization and realistic visual performance, and its important 3D analysis and 3D operation functions are also very limited.
The construction of three-dimensional spatial databases is still a complex and expensive comprehensive project. The production efficiency, quality control, data security, and effective storage and management of large 3D GIS systems are becoming increasingly prominent, and are directly related to the success or failure of system construction and application. The three factors that determine the specific production scheme of spatial data are precision, cost, and efficiency, the usefulness and spatial analysis capabilities of the final system depend on the realism of the model and the selected data source and modeling method. Therefore, the lack of technical standards related to data content, details, positioning accuracy and production technology in 3D GIS has become one of the key issues restricting its application.
3D GIS provides three-dimensional visual recognition, and provides more profound spatial analysis functions, the lack of new 3D spatial analysis methods and functions is one of the main bottlenecks Restricting the more extensive and in-depth use of 3D GIS.
3D GIS has its own advantages in 3D data visualization. Compared with 2D GIS, it has weak functions in 3D modeling, 3D operations, and 3D analysis; however, 3D object reconstruction, representation and navigation of large-scale 3D model data, and data editing and organization are still bottlenecks.
The capability of complex analysis and decision support based on 3D spatial data is still weak, and the networking and standardization of 3D GIS need to be further deepened and improved.
Several modeling methods
3D building model reconstruction methods are divided into the following three types:
1) Based on the map method, the box-like model is quickly established using the 2D plane data and other highly-assisted data provided by existing GIS, maps and CAD. The advantage is that the modeling speed is fast and the automation degree is high. The disadvantage is that the model is rough and the box model.
2) the image-based method uses close-range, aerial and remote sensing images to establish a realistic surface model including top details. This method is relatively time-consuming and expensive, and the automation degree is not high.
3) the node group method, using a large number of 3D point group data quickly obtained by Laser Scanning and Ground Movement Measurement to establish a three-dimensional reconstruction data source for the GPS Positioning Model of the geometric surface, data can also be divided into remote data acquisition (satellite images, aerial images, no-load laser Scanning, etc), close-range data (close-range photography, close-range laser scanning, manual measurement) and GIS/CAD export data (Brenner and haala, 2001; sh2iode, 2001 ). Different data sources correspond to different three-dimensional model details and application scopes. For example, the method based on remote sensing images and airborne laser scanning is used to obtain a wide range of 3D model data; the method of on-board digital photography is suitable for corridor modeling; the ground photography measurement method and the close-range laser scanning method are suitable for fine modeling of complex objects. The 3D model acquisition method based on the image and airborne laser scanning system can be used to quickly obtain geometric models and texture details of the ground and buildings in a wide range of regions, although the existing technology relies heavily on manual assistance, it is undoubtedly one of the most promising technologies for automatic acquisition of 3D model data. The Simple Modeling Method Based on existing 2D GIS data has the advantages of low cost and high automation. It is also widely used in some fields that require rapid establishment of 3D models, this is also the most important way that most of the existing 2-dimensional GIS provides 3-dimensional capabilities. The CAD-based human-machine interactive modeling method will continue to be used for 3D and realistic reconstruction of complex artificial targets. In addition, Image Based Modeling & rendering: ibmr is a new visual modeling method, you can also obtain highly realistic scene expressions without complex geometric models, it can better solve the conflict between the complexity of the model and the realistic and real-time rendering in the Three-dimensional modeling process, greatly simplifying the complex data processing work. Therefore, it is increasingly used for the establishment of various virtual environments. In particular, two modeling technologies based on graphics and images are integrated for the creation of highly realistic 3D landscape models. The above technology is mainly used to reconstruct the three-dimensional surface model of the target, professor Wu Lixin gave a detailed introduction to the true 3D reconstruction technology in the field of earth science in his article "Several Problems of true 3D geosimulation.
A realistic three-dimensional representation not only provides geometric expressions with multiple levels of details, but also provides a surface description with a photo texture, such as realistic materials, texture features, and other related attributes (Gruber and wilmersddorf, 1997). Therefore, texture and material parameters are important to the database. The integration of a large amount of raster data and vector data results in a sharp increase in data volumes. The word "massive" is the most vivid description of this, the "massive" refers to the amount of data that far exceeds the core memory capacity of the computer. To meet the real-time requirements of 3D visual interaction, effective management and scheduling of massive data has become one of the key technologies of 3-dimensional GIS, such as analyzing the underground structure, history processes that won't be re-retrieved, deriving future development, and Simulating Complex Time-Space phenomena (typhoons evolution, flood, air pollution, impact of nuclear power plant leaks, noise propagation, temperature and wind field changes) so as to obtain a variety of space sensing beyond the reality through casual rotation, scaling, and moving operations are often prone to lost orientation, making it difficult to quickly locate. In order to enjoy a superior sense of attention in conventional 2D GIS maps, and to gain a sense of realism and immersion in 3D realistic display, multi-view multi-mode visual view is the most typical interface feature of 3D GIS. Compared with macro overflight roaming, it can quickly grasp the entire spatial distribution, including topographic features and geographical layout; compared with the microscopic walk-through roaming, it can accurately distinguish the minor changes of the terrain and the obvious features of the terrain, in addition, the visible content can be updated in a timely manner during the movement and displayed in different details or scales according to the distance. Graph-based spatial analysis methods, such as regular buffer analysis, stacked analysis, network analysis, composite analysis, and adjacent analysis and spatial connection, can be directly extended from 2D to 2. 5D or 3D. Because dimension 3 data can be reduced to dimension 2, dimension 3 GIS can naturally accommodate the spatial analysis function of dimension 2 GIS. The most distinctive feature of 3D GIS is its complex analysis capabilities based on 3D data, such as calculating spatial distance, surface area, volume, accessibility and accessibility. Combined with physical and chemical models, it provides some real 3-dimensional spatial analysis functions with more value-added values, such as hydrological analysis, visual analysis, Rizhao analysis, and visual landscape analysis, it has become one of the most important aspects of 3D GIS analysis, and most of them are limited to the application scope of visual performance. In fact, compared with 2D GIS, 3D GIS features multidimensional information processing, expression, and analysis, in urban emergency response, virtual tourism, intelligent transportation, urban planning and design, e-commerce and residential district management, wireless communication base station site selection, city micro-climate and air pollution simulation, noise analysis, geological and underground pipeline and other aspects have a very broad field, especially in the social service of spatial information, the applications based on 3D GIS have more and more obvious advantages and irretrievability in complex analysis and decision support based on 3D spatial data, the networking and standardization of 3D GIS need to be further deepened and improved.