The essence of GIS is to query, analyze, process and display all kinds of information on the basis of expressing the real world in an intuitive way, so that people can make scientific decisions. After more than ten years of development, the superiority of two-dimensional GIS technology in business management and work efficiency has been widely recognized, and has been successfully applied in dozens of industries in China. 2D GIS uses (X, y) to represent spatial location, while 3D GIS uses (X, y, Z) to represent spatial location. Compared with 2D GIS, 3D GIS not only provides 3D visual cognition, but also provides 3D Spatial Analysis methods and functions. With the development of computer technology and the in-depth application of two-dimensional GIS industry, people gradually show the desire to use three-dimensional GIS to show the real world. Moreover, 3D GIS has more and more obvious superiority and irreplaceability in military battle command, electronic sand table and terrain simulation, digital city, real estate display, thematic analysis and simulation of environmental protection and meteorology, urban microclimate and air pollution simulation, geology and Underground Pipelines, etc.
The current three-dimensional GIS is not only a synonym for fashion, it has indeed entered the practical and industrial era, the rapid development of three-dimensional GIS technology will undoubtedly lead to a new generation of GIS technology tremendous changes. However, compared with 3D GIS, 2D GIS data model is simpler, more abstract and more comprehensive. For a long time, 2D GIS alone can not meet the needs of future development. Similarly, 3D GIS alone can not meet the application requirements at present. Therefore, the development of two-dimensional and three-dimensional integrated GIS software, not just an independent three-dimensional GIS, is the future development direction of GIS software. The GIS software with the characteristics of 2D and 3D integration, whether it is called 2D GIS software or 3D GIS software, is not comprehensive, which requires the introduction of a new concept-real space GIS.
Realspace GIS is relative to PaperSpace GIS. The so-called paper space refers to the paper coordinate space after projection. Correspondingly, paper space GIS refers to GIS software based on the projected paper map coordinate space. The so-called true space refers to three-dimensional geographic space and two-dimensional map space based on geographic sphere or ellipsoid. Real space GIS refers to GIS based on three-dimensional geographic space and two-dimensional map space based on geographic sphere or ellipsoid.
Compared with 2D GIS, 3D GIS has the following advantages:
- Advantages of display effect: Two-dimensional GIS needs to be projected on the plane and represented by symbols, and it can not express the ups and downs of the terrain, nor can it represent high-altitude or underground features, nor can it simulate natural phenomena such as light, smoke, water and so on. Three-dimensional GIS can describe the real world without projection, express the surface features and natural phenomena that two-dimensional GIS can not express, which is more vivid and intuitive, and more conducive to the popularization of GIS.
- Advantages of Analytical Decision Making: On Spatial Analysis, 2D cannot realize the analysis functions on true 3D space, such as Flood Analysis, Terrain Analysis, Sunlight Analysis, Spatial Diffusion Analysis, Intervisibility Analysis, etc. 3D GIS not only fully integrates 2D Spatial Analysis functions, but also breaks through the constraints of the monotonous display of Spatial Info in the 2D plane, which provides a better way for information interpretation and Spatial Analysis, and also provides more intuitive decision support for various industries.
Indispensable 2D GIS in the Near Future
In recent years, with the development of CPU technology and the emergence of high-performance visualization algorithms, the speed of 3D large-scale scene visualization has been greatly improved, and the great development of aerial and close-range photogrammetry provides a data base for the development of 3D GIS, which makes 3D GIS develop rapidly and gradually enter the practical stage. However, two-dimensional GIS, which has been developed since the 1960s, is undoubtedly the part that new and old GIS customers can not give up in terms of function, performance, data and application. Two-dimensional GIS has simple data model, a large number of valuable Spatial Data, rich Map Cartography functions, a variety of query, analysis and decision-making methods, and mature business application processes, which are destined to be in a considerable period of time. It is difficult for 3D GIS based on visualization to completely replace 2D GIS.
In addition, compared with 2D GIS, the acquisition cost of 3D Spatial Data is more expensive, especially for large-scale 3D Scene modeling. Secondly, compared with 2D GIS, 3D Data model is more complex, which leads to the low efficiency of algorithms based on 3D Spatial Query and analysis function; Finally, due to the limitations of network transmission and massive Data Management, 3D GIS has not yet met the requirements of "real-time".
Realspace with 2D and 3D integration
Based on the respective advantages of 2D and 3D GIS, people often want to include 2D and 3D functions in one system. However, as far as most three-dimensional systems are concerned, even though they contain three-dimensional and two-dimensional display parts, they are essentially independent of each other. It is embodied in three aspects: data, representation method and analysis function, which undoubtedly brings huge cost and difficulty to the application of GIS. The main reason for this problem is that most of the current three-dimensional systems are separated from the mainstream large-scale two-dimensional GIS platform. To solve these problems, we must start from the underlying technology of GIS platform to achieve the integration of two and three dimensions.
Features of Real space
Compared with the two-dimensional GIS, which projects the real space to the two-dimensional plane for expression and analysis, the Realspace technology introduced by SuperMap does not need projection, and directly loads the longitude and latitude data to the three-dimensional sphere for display, which is the real three-dimensional geographic space display. Realspace grows up on the basis of SuperMap large-scale GIS platform, combines the most advanced computer software and hardware technology and three-dimensional visualization technology, and has the characteristics of more powerful function, more superior performance and more realistic effect.
Real space GIS is not only three-dimensional, but also two-dimensional and three-dimensional integration. The 2D and 3D integration of real space GIS is reflected in:
- 2D and 3D data models and data structures are integrated, and all 2D data can be directly visualized in 3D Scene with high performance without any conversion processing, which not only requires 3D GIS to be compatible with 2D data structures, At the same time, the 2D data structure should be properly adjusted to realize the high performance visualization of massive 2D data in 3D Scene;
- All 2D GIS analysis and processing functions can be directly operated and used in 3D Scene.
Executive summary
Two-dimensional and three-dimensional display integration