## 2 DC Construction under the Demand of Modernization
### The Main Content of DC Construction in the IoT Environment  
Geospatial frameworks will face new opportunities and challenges with the progression of the times, the progress of technology, and the change in human needs. First, the popularity and universality of geographic information is overwhelming, and users are no longer limited to professionals with certain mapping knowledge. It has begun to spread to the masses, and new products that focus on fine 3D quality, panoramic images, and better experience 3D technology are easily accessible to the masses [36]. Second, although the geographic information public platform in DC solves the problem of continuous spatial expression in the real world, it still has a time lag. [PERSON] [37] suggested that with the progression of spatial sensing expansion, such as real-time positioning, IoT, and radio frequency, effective means are provided to integrate real-time information so that the mapping is continuous in the time dimension and can trace back the past, express the present, and predict the future more accurately. Third, with the progression of wireless networks and intelligent terminal technology, machine-centered cities are meant to change into human-centered models. The advent of the mobile office era will help anyone control anything within their jurisdiction in real-time, anytime, and anywhere in the future [38; 39; 40]. Fourth, the digital system will no longer adhere to the general query, positioning, statistics, and analysis but will rely on IoT, sensor network, and other in-depth knowledge mining, support scientific decision-making and issue remote control commands to respond to the real world through the analysis and judgment of the digital world [41; 42]. Finally, regarding the practical application, the system can make scientific and accurate analyses when ordinary users make requests. Additionally, the computing resources and network resources distributed on each network node can be collected automatically to realize intelligent combinations driven by knowledge and provide services for social needs. [PERSON] et al. [43] suggested that the construction of DC is inseparable from the support of the geospatial framework, which is the responsibility of the Department of Surveying and Mapping Geographic Information as well as the infrastructure of urban information. In the DC stage, the main content of the geospatial framework is the basic geographic information database and geographic information public platform. [PERSON] et al. [44] mentioned that with the progression of IoT and cloud computing, basic geographic information databases are transformed into spatiotemporal information databases, and geographic information public platforms are upgraded to spatiotemporal information cloud platforms. The spatiotemporal information database consists of spatiotemporal information data, IoT node address data, a spatiotemporal information database management system, and a support environment. Moreover, a spatiotemporal information cloud platform can provide geographic information, IoT, and node location and develop functional software and interfaces for ubiquitous application environments via visualized fine geographic information and temporal geographic information covering the whole society [45; 46; 47]. Compared with geographic information public platforms, spatiotemporal information cloud platforms have better experience, real-time mobility, controllability, and automation. The IoT is a new connection mode established under the Internet of Information and mobile Internet. It originates from the internet and depends on the extension of its boundary and connotation. The IoT changes the situation in which all information on the internet is acquired and created by people, and all items need human instruction and operation, which will profoundly affect every aspect of production and life in the future. In the future, the scale of the interconnection of things in the world will be much larger than the scale of the interconnection of people.