How to Build a 3D City by Moving a 3D City into a Digital Space Realistic Scene? One article to read

With the continuous development of surveying and mapping geographic information technology in China, China is accelerating the construction of a new basic surveying and mapping system, and comprehensively promoting the construction of realistic 3D China. The reporter learned from the Ministry of Natural Resources that as of now, 264 cities in China are carrying out urban level 3D model construction, and various scene applications are constantly enriched

With the continuous development of surveying and mapping geographic information technology in China, China is accelerating the construction of a new basic surveying and mapping system, and comprehensively promoting the construction of realistic 3D China. The reporter learned from the Ministry of Natural Resources that as of now, 264 cities in China are carrying out urban level 3D model construction, and various scene applications are constantly enriched.

Real 3D, in short, is to build a city in the digital world exactly like the reality. It is a 3D digital map in the real scene. It can comprehensively and stereoscopically present the status quo and spatial distribution of various natural resource elements in these cities.

Zhang Jixian, Director of the Department of Land and Mapping of the Ministry of Natural Resources:(These cities) produce 5 to 10 centimeter resolution oblique photography 3D models and underground pipeline data within the built-up area, while accessing IoT sensing device data to support urban planning, construction, services, and management. For example, Xi'an City has carried out dynamic monitoring of the boundary demarcation of the Giant Panda National Park and illegal construction projects on Qinling North Road, based on real-life 3D results, focusing on environmental protection and ecological restoration at the northern foot of the Qinling Mountains.

How is realistic 3D generated?

As one of the earliest cities to carry out real 3D construction, Chongqing has now achieved the transfer of 82400 square kilometers of mountains, rivers, and three-dimensional cities to digital space. So, how did you build a realistic 3D model with such a wide area? Let's get to know together.

It is understood that the real 3D construction tasks in China are mainly divided into three categories: terrain level, urban level, and component level. Both terrain level and urban level require aerial photography as one of the main data sources. On site, the reporter followed the surveying and mapping personnel to experience the entire process of generating real 3D scenes. In order to ensure the accuracy and three-dimensional nature of aerial photographs, surveying and mapping personnel must first prepare for a series of preparations such as on-site investigation and image control point measurement before collecting data.

Xue Mei, Vice President of Chongqing Institute of Surveying and Mapping Science and Technology:Now we can see many slender stripes on the screen, which represent the path and direction of our designed future drone shooting. If we zoom in on these stripes, we can see that they are composed of many small points, each representing the moment when the future drone presses the shutter above that point during shooting.

During the shooting process, aerial photography images specifically used for real-life 3D scenes are also different from ordinary photos. Each shot has five tilted cameras simultaneously pressing the shutter, and in addition to the vertical viewing angle, they also take photos on four sides to obtain more rich ground information.

Xue Mei, Vice President of Chongqing Institute of Surveying and Mapping Science and Technology:Now let's take a photo from the area we just shot and zoom in on it with a vertical downward angle. You can see up to 5 centimeters of objects on the ground, such as the road you are seeing now. Not only can you see the signs and markings on the road, but even the traffic signs on it are clearly visible.

According to estimates, to produce such a realistic 3D image, nearly 40000 photos need to be taken for every 10 square kilometers of area. After completing the image acquisition, the surveying and mapping personnel will preprocess the photos, and then use a computer to parse the massive data into 3D model tiles, ultimately splicing to complete the real 3D modeling.

Realistic 3D gradually applied to diverse scenes

Realistic 3D integrates digital space and real space, providing more possibilities for urban data applications. In Wuhan, we have just equipped the latest equipment to generate virtual videos in real time using real 3D technology. Let's watch the reporter's experience together.

CCTV reporter Wei Xiaowan:The realistic 3D map of a city is usually presented in a static form in front of everyone, but currently, Wuhan can present this 3D map in the form of panoramic videos. And these are achieved through the professional equipment carried on the car next to me. As I walked around, the geographic coordinates of the buildings around me were presented in real-time on the screen. This was achieved by matching the image positions of these buildings in the video stream with the electronic map, making it look more intuitive.

Wang Shan, Senior Engineer of Wuhan Surveying and Mapping Research Institute:With the support of 5G communication technology, video streaming panoramic maps will be an important manifestation of next-generation internet maps. For example, when commanding rescue operations, we can send drones over and use them to capture a panoramic video stream map of the area. Through it, we can rotate 360 degrees to see what the entire scene looks like, making it easier for the commander to make decisions.

At the same time, real-life 3D can also play a role in urban planning and design by linking with natural resources, socio-economic and other data. Taking the Wuhan Three Town Center project as an example, it is located in the core commercial district of Wuhan City, with a large flow of people and vehicles on the ground and dense surrounding buildings. Under the ground, there are also subway lines and municipal pipeline networks, making construction difficult.

Wu Sumin, Project Leader of Wuhan Realistic Three Towns Construction:By using a realistic 3D model and integrating the above ground and underground modes, the surrounding construction situation, geological structure stratification, and underground pipeline network of the project are presented in a real, three-dimensional, and objective manner, providing a design basis for providing the best planning and design scheme, while effectively preventing damage to the subway and underground pipeline network caused by future construction.

Guo Mingwu, Deputy Director of the Basic Geographic Information Center of Wuhan Surveying and Mapping Research Institute:We can intuitively analyze the spatial coordination between our construction plan and surrounding buildings, as well as whether the planning indicators such as lighting, building density, and plot ratio meet the requirements, by incorporating the building plan into our large scene.

When will the live 3D online system be fully launched?

It is understood that the construction of real 3D in China is far from just building a digital model of the city. So, in what areas will the future development of real 3D in China go? When is it expected that the real-time 3D online system will be fully launched?

At present, the Ministry of Natural Resources has also successively introduced a series of technical outlines to promote the expansion of real-time 3D data coverage from the land surface to the overall spatial integration of land and sea. The Ministry of Natural Resources stated that by 2035, all national and provincial city/county multi-level real-time 3D online systems will be launched, and cities at or above the prefecture level and county-level cities with conditions will achieve real-time connectivity between digital space and real space.

Zhang Jixian, Director of the Department of Land and Mapping of the Ministry of Natural Resources:We will actively guide supply side technological innovation, improve the technical standard system, coordinate the rapid construction of urban 3D models, strengthen application services, and build a realistic application ecosystem for 3D China construction to form a new pattern of socialized services.

(CCTV reporter Cui Xia, Tan Zhenhua, Jin Xiaoxi, CCTV reporter Xia Siwei, Jin Zhu)

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