Charting Hong Kong’s nooks and crannies

Photo: Yongyuan Dai/iStock/Getty Images Plus/Getty Images

Team Provides Accurate 3D Maps for Smart City Applications

The PolyU team’s mobile mapping backpack. (Image: The Hong Kong Polytechnic University)

According to 2019 statistics, more than 10,000 residential buildings in Hong Kong are at least 50 years old. Most of these buildings lack 3D indoor building information models (BIM), which creates challenges when it comes to reconstruction or maintenance.

In response, a team at Hong Kong Polytechnic University (PolyU) has developed a lightweight and reliable 3D mobile mapping system in a backpack. The system can easily measure cities and obtain 3D maps with centimeter-level accuracy. It can be used to build spatial data infrastructure, which supports smart city applications in many fields.

The system uses advanced technologies such as simultaneous localization and mapping (SLAM), useful in urban canyons where GNSS signals can be spotty. It can carry out continuous data collection in complex indoor and outdoor environments, and is particularly suitable for high-density and complex urban environments, such as those in Hong Kong.

The mapper is providing a special boon to modular integrated construction (MIC) in the city. With MIC, free-standing integrated modules are prefabricated and then transported to the site for installation in a building. However, the trucks hauling the large components can’t always maneuver through narrow streets in Hong Kong’s urban areas.

One of many narrow streets mapped in downtown Hong Kong. (Image: The Hong Kong Polytechnic University

To address the issue, the PolyU team collaborated with the Hong Kong Construction Industry Council, providing its mobile-mapping backpack to conduct 3D measurement of critical road sections. The project identified and mapped obstacles, and optimized the route for transporting oversized components to avoid narrow passages.

Mobile-mapping backpacks also can be used to create detailed indoor 3D models to support firefighting and provide evacuation routes for personnel at the fire scene.

The route taken by the mobile mapping backpack carrier in the harbor area. (Image: The Hong Kong Polytechnic University)

A sample point cloud from the mobile mapper. (Image: The Hong Kong Polytechnic University)

The mobile mapper is one of the technologies developed by PolyU’s Smart Cities Research Institute, established in 2020 to help address social issues and provide solutions for smart city development. In March, the institute’s projects received a gold medal at 2021 Inventions Geneva Evaluation Days.