South Korean smart cities combine 3D digital models with GIS and BIM

作者：琳达·达菲（Linda Duffy）

Around the world, local governments are rolling out Smart City/Digital Twin projects to support economic stimulation and tourism programs and to improve the quality of life overall. Up-to-date 3D building models and comprehensive Geographic Information Systems (GIS) data, along with Building Information Modelling (BIM) data, are combined to create a digital twin of the inside and outside of buildings and the surrounding topography. In effect, the real world is converted into an exact digital replica to facilitate analysis, planning and management of all smart city assets.

The primary goal behind 3D virtual cities is to reduce and manage problems typically found in urban areas by conducting simulations and analysis on digital twins and using the results to improve conditions. In addition, big data captured with Internet of Things (IoT) sensors, closed-circuit television (CCTV), security cameras, etc., provide insight into specific locations. The South Korean government started its Smart City/Digital Twin program in 2017 to address various issues, such as traffic, crime, environmental pollution, efficient energy management, urban planning, disaster management, and redevelopment. By analysing the virtual cities and associated big data, governmental entities are better equipped to address areas of concern.

Building a digital twin

All4Land是韩国领先的地理空间服务提供商，一直在建立包括BIM和GIS数据在内的3D数字模型。为了节省时间并降低成本，All4land同时收集倾斜和激光雷达数据Leica CityMapper机载映射传感器并快速处理数据Leica HxMap，一个多传感器处理平台。通过GIS数据（例如公用事业，电信或运输基础架构的矢量图）增强了所得的3D模型，以支持深入分析。建筑物的外部形状由CityMapper数据制成，内部形状由3D扫描数据，设计数据和BIM数据制成。

All4Land is responsible for creating the GIS data and 3D building models and integrating BIM data provided by the building owner or a government agency. BIM data is mandatory for new government construction in Korea and is normally produced by a 3rd party design office. For new buildings, BIM is typically captured during and after the construction process, and for existing buildings it is established by reverse engineering with 3D scanning and original design data.

组合的CityMapper和HXMAP解决方案基于CityGML的详细信息1（LOD1）和LOD2提供自动处理，这是一种开放数据模型和基于XML的格式，用于存储和交换虚拟3D City Models。LOD3需要一些手动处理来表达大门和窗户等开放元素，而LOD4涉及的手动处理取决于室内细节的水平。

“ HXMAP中具有强大的功能，尤其是在多个相机的同时进行空气三角调节处理中，以及来自图像和激光雷达数据的有效3D建模，” All4land董事总经理Sangkwam Nam说。“ HXMAP还支持处理任务，例如传感器校准，自动点匹配，线路对线注册，建筑生成等。所有这些都是以前乏味的手动任务，现在可以在HXMAP工作流程中自动运行。”

To combine CityMapper data with BIM data, All4Land first allocates coordinates derived by GNSS surveying to the BIM data, then converts the BIM data to 3D building models and merges them with CityMapper data. All4Land developed its own proprietary software for data conversion and coordinate allocation and makes the 3D models available through its MapPrime platform, a WebGIS server that integrates indoor and outdoor models and provides data visualisation tools.

CityMapper LiDAR Point cloud (Point density : 25 point/㎡)

全场的3D模型

In 2019, with its purchase of a highly efficient CityMapper aerial system and HxMap, All4Land became well-positioned to expand its 3D mapping services. Collecting data quickly is particularly important because of the unique limitations of aerial data capture in South Korea. Surrounded by the sea on three sides, cloud cover in South Korea frequently creates unfavourable weather conditions. In addition, it is difficult to get flight permission near military zones and security areas, therefore total flying days are quite limited. Under these circumstances, the CityMapper’s ability to capture orthophotos, oblique imagery and LiDAR all in one flight is advantageous.

“The CityMapper is an excellent solution for our projects ─ the added efficiency allows us to capture more data in a shorter period of time,” says Nam. “And HxMap streamlines the processing and modelling, which reduces the cost of building a digital twin.”

One of the test projects for the Digital Twin concept was in the city of Jeonju, a tourist area in North Jeolla Province in southwestern South Korea. Many historic buildings, such as the traditional village called Hanok, attract visitors, and the city is known for its excellent regional cuisine. Recently Jeonju introduced the Digital Twin concept as part of MaaS (Mobility as a Service) to attract tourists and help them travel around the city using electric bicycles, electric kick boards, and other transportation.

All4land被选中在全都进行了两个项目，首先绘制一个面积为4平方公里（平方公里）的区域，其中包括BIM的20座建筑物，然后是205平方公里的项目。政府会长组织Jeonju和LX市正在为大型地区所有政府拥有的建筑物获取BIM数据。使用CityMapper，该大型项目的空中数据捕获仅花了两天时间，而数据处理和3D建筑建模又有2到三个月。用CityMapper捕获的LOD3室外数据与测试区域中的室内BIM数据合并，以创建现实世界的LOD4模型。

“Digital twins are helpful for many applications,” Nam stated. “For example, before planning a new building in a downtown area, the simulation model is utilised to analyse the 360-degree view, visibility range, solar rights, privacy issues, etc. This uncovers any potential conflict with existing buildings. The development plan can be revised and improved in the early stages, which saves money in the long run.”

3D Building Model

Smart cities are the future

当今韩国大约有十个智能城市项目，预计数量将增加。除了全球外，All4land还在为韩国首尔市的虚拟汉城项目和韩国国家地图局（NGII）的3D地理空间项目（NGII）工作。

韩国智能城市关注的vitalisationthe local economy based on smart mobility, demographics, tourism, and other factors. Government organisations use the 3D building models to analyse options and opportunities to support decision making. In the future, All4Land expects the MapPrime platform to be open to commercial companies for the management of facilities, parking, sightseeing, etc.

The expanded use of digital twins relies on efficient collection of data and highly automated processing to keep costs reasonable. Leica CityMapper, and the more recent CityMapper-2, are high-performance urban mapping sensors ideal for fast digitisation of cities and urban environments. The hybrid oblique imaging and LiDAR solutions, paired with the HxMap processing platform, together provide high productivity and fast turnaround.

“We are very satisfied with the CityMapper’s performance and data quality ─ the nadir and oblique images and LiDAR are excellent. We also feel that technical support and training programs offered by Leica Geosystems are the best,” says Nam. “Leica Geosystems keeps supporting customers, trying to find better solutions together during the entire process of operation and processing, and that helps us stay competitive in a rapidly changing industry.”

CityMapper LiDAR Point cloud (Point density : 25 point/㎡)