The essence of GIS is to inquire, analyze, process, and present all kinds of information based on expressing the real world in an intuitive way to help people to make scientific decisions. After more than ten years of development, the superiority of 2D GIS technology in business management and work efficiency has been widely recognized and successfully applied in dozens of domestic industries. 2D GIS uses (x,y) to represent spatial location. 3D GIS uses (x,y,z) to represent spatial location. Compared to 2D GIS, 3D GIS not only provides 3D visual perception, but also provides 3D Spatial analysis methods and functions. With the development of computer technology and the in-depth application of 2D GIS industry, people have gradually demonstrated the desire to use 3D GIS to display the real world, and 3D GIS in military operations command, digital sand table and terrain simulation, digital city, real estate display, environmental protection There is an increasingly obvious superiority and irreplaceability in areas such as thematic analysis and simulation in meteorology, urban microclimate and atmospheric pollution simulation geology and underground pipelines.
The current 3D GIS is not only synonymous with fashion and fashion, it has indeed entered the era of practical and industrialization. The rapid development of 3D GIS technology will undoubtedly lead the great changes in a new generation of GIS technology. However, compared to 3D GIS, the 2D GIS data model is simpler, more abstract, and more comprehensive. For a long period of time, a single 2D GIS cannot meet the needs of future development. Likewise, a single 3D GIS cannot meet the requirements at present application requirements. Therefore, the development of 3D integrated GIS software rather than just an independent 3D GIS, is the future direction of GIS software development. GIS software with both 2D and 3D integration characteristics, whether it is called 2D GIS software or 3D GIS software, is not comprehensive, which requires the introduction of a new concept Realspace GIS.
Realspace GIS is created relatively based on PaperSpace GIS. The so-called paper space refers to the paper image coordinate space after projection. Correspondingly, paper space GIS refers to GIS software based on the projected paper image coordinate space. The so-called "Realspace" refers to 3D geographic space and 2D map space based on geographic sphere or ellipsoid. Vacuum GIS refers to GIS based on 3D geographic space and 2D map space based on geographic spherical or ellipsoidal plane.
3D GIS have the following advantages over 2D GIS:
- Advantages of Display Effect: 2D GIS needs to be projected onto a plane and expressed by means of symbols, and it cannot express terrain ups and downs, features that cannot represent high altitude or underground ground, and cannot simulate natural phenomena such as illumination, smoke, flowing water, etc. . . . The 3D GIS can describe the real-world appearance without projection, express the features and natural phenomena that cannot be expressed by the 2D GIS, and become more visual and intuitive, which is more conducive to the popularization of GIS.
- Advantages of Analysis and Decision-making: In spatial analysis, 2D analysis functions such as flood analysis, terrain analysis, sunshine analysis, spatial diffusion analysis, and visibility analysis cannot be implemented in true 3D space. 3D GIS not only fully integrates the 2D spatial analysis function, but also breaks through the shackles of monotonous display of spatial information in 2D planes, provides a better way for information interpretation and spatial analysis, and can also provide more intuitive for various industries. Assisting decision support.
Irremediable 2D GIS for Near Future
In recent years, with the development of CPU technology and the emergence of high-performance visualization algorithms, the visualization speed of 3D large-scale scenes has been greatly improved, and the great development of aviation and close-range photogrammetry has provided the data foundation for the development of 3D GIS. This makes the 3D GIS get rapid development and gradually enters the practical stage. However, the 2D GIS that developed from the 1960s is undoubtedly a irremediable part for new and old GIS users in terms of its functions, performance, data, and applications. 2D GIS has a simple data model, valuable large amount of spatial data, rich map mapping functions, a variety of queries, analysis and decision-making methods, and mature business application processes. These are doomed to visualize in a very short period of time. The main 3D GIS are difficult 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, 3D data model, compared to 2D complexity, leads to 3D spatial query and analysis functions. The efficiency of the algorithm is low; finally, due to the limitations of network transmission and mass data management, 3D GIS has not yet reached the requirement of "real-time".
Realspace under 2D 3D Integration
Based on the respective advantages of 2D and 3D GIS, people often want to include both 2D and 3D functions in one system. However, for most of today's 3D systems, even if they contain 3D and 2D display parts, they are essentially independent from each other. It is embodied in three aspects: data, performance methods and analysis functions. This undoubtedly brings huge costs and difficulties for the final GIS applications. The main reason for this problem is that most of the current 3D systems and mainstream large-scale 2D GIS platforms are fragmented. To solve these problems, we must start with the underlying technology of the GIS platform to achieve the integration of 2D.
Features of The Realspace Technology
Compared to 2D GIS, the "Realspace" is projected onto a 2D plane for expression and analysis. The "Realspace" technology introduced by SuperMap, it directly loads latitude and longitude data onto a 3D spherical plane without projection, and is a true 3D geographic space display. "Realspace" grows based on the large GIS platform of SuperMap. Combining the most advanced computer hardware and software technologies and 3D visualization technology, Realspace has more powerful features, superior performance and more realistic features.
The features of Realspace combining 2D and 3D are:
- The 2D and 3D data models and data structures remain integrated. All 2D data do not require any conversion processing and can be directly visualized in 3D scenes. This requires not only 3D GIS-compatible 2D data structures, but also two The dimensional data structure should also be properly adjusted to achieve high-performance visualization of massive 2D data in 3D scenes;
- All 2D GIS analysis and processing functions can be directly manipulated and used in 3D scenes.
Executive Summary