Today is the sixth day of the Lunar New Year. Let me start by wishing you all good health and all the best throughout the year. In our daily lives, we get accustomed to searching routes with mobile maps, or locating car parks, bus stops and the like with applications in our mobile phones. All these involve the use of “spatial data” with reference to a specific geographical location. The Lands Department (LandsD) has been striving to press ahead with the development of the Common Spatial Data Infrastructure to facilitate the consolidation, exchange, sharing and innovative application of geospatial information, and to launch a territory-wide 3D digital map in phases. Earlier on, the 3D Pedestrian Network and the 3D Visualisation Map have been made available to the public for free. In this post, I have invited Mr CHU Siu-ki, Alex, Assistant Director (Survey and Mapping) of the LandsD, to give us a detailed briefing.

A real city built in a digital environment

Compared with a plane map, a 3D digital map is more informative and precise, which is simply the replica of a real city built in a digital environment. It manifests the cityscape of Hong Kong with fine details, enabling users to view the exterior features of buildings from different angles, take measurements and retrieve relevant geographical information. Various data collected from sensors, such as temperature, wind directions and noise, can be incorporated into 3D digital maps to support a wider range of applications and analyses.

Developing three 3D digital map products

The LandsD has been progressively developing three 3D digital map products, namely, (i) the 3D Pedestrian Network; (ii) the 3D Visualisation Map showing exterior features of terrains, buildings and infrastructures; and (iii) the 3D Indoor Map.

3D Pedestrian Network measuring 8 300 km in length

Mr Alex CHU says the 3D Pedestrian Network, now measuring 8 300 km in length, covers publicly accessible places (including footways, footbridges, subways, unpaid areas of all MTR stations, parks and selected passages of shopping centres connected to publicly accessible places) in urban areas of Hong Kong and on five main outlying islands, namely, Lantau Island, Lamma Island, Cheung Chau, Peng Chau and Ma Wan. The entire network is a set of 3D line features capable of supporting various innovative technologies such as navigation with Augmented Reality and voice navigation, and facilitating a wider range of applications than 2D data does. It can be used for purposes ranging from simple route planning and new application development to urban or road planning studies.

Catering for the needs of wheelchair users

Mr Alex CHU says that given the innumerable overpasses and steep roads in Hong Kong, a plane map may not be able to show the details of every route. Harnessing 3D data, the 3D Pedestrian Network can identify ascending and descending footways, indicate the length of a footpath, and offer other functions. This greatly enhances the accuracy of calculating the required walking time, thereby enabling users to search for the fastest and the more straight forward routes. In addition, the 3D Pedestrian Network also provides information such as the barrier-free access to public facilities and locations and opening hours of public lifts for wheelchair users to search for befitting routes. For maintaining the quality, the information will be updated at three-month intervals.

Extending coverage to hiking trails and releasing data progressively during the year

MyMapHK, a mobile map application developed by the LandsD, currently provides the public with a route search function under the 3D Pedestrian Network. Members of the public and application developers can also download free of charge the 3D Pedestrian Network from the Public Sector Information Portal (data.gov.hk) and the Hong Kong GeoData Store (geodata.gov.hk) maintained by the Government to devise mobile applications. According to Mr Alex CHU, the LandsD is enhancing the 3D Pedestrian Network, with its first task being the extension of its existing coverage from urban areas to rural areas and hiking trails in country parks. Opening hours will also be incorporated into the existing indoor pedestrian network for more accurate route searches. The optimised data will be released progressively during the year.

3D Visualisation Map

Meanwhile, the LandsD is pressing ahead with the development of a next- generation 3D Visualisation Map with the aim of covering the entire territory progressively by the end of 2023. Mr Alex CHU says the 3D Visualisation Map developed by the LandsD not only makes use of aerial photographs taken from an aircraft, but also combines them with the images captured on the ground and data collected by laser scanners. With these, the 3D Visualisation Map displays and links the locations of facilities built overhead, on and even below ground level, along with related spatial data, to create 3D models that have higher resolutions and are truer to life with an accuracy of around plus/minus 1 metre.

Supporting technical assessments

The 3D Visualisation Map manifests Hong Kong’s cityscape with fine details by showing the exterior features of terrains, buildings and infrastructures from different angles. Complementing more effectively other geospatial data like information from various government departments, the 3D Visualisation Map supports urban planning, land administration, project development, environmental studies, transport/traffic studies, landscape design and other technical assessments, and facilitates the development of various applications, thereby fostering the future development of Hong Kong society as well as developing the territory into a smart city.

3D Indoor Map

In addition, the LandsD has produced the 3D Indoor Map for 158 buildings primarily located in Kowloon East under a pilot project. It plans to produce the same for 1 250 buildings across the territory, covering premises for provision of public services such as hospitals, clinics, libraries and performing venues, by the end of 2023.

A survey vehicle for capturing street views

Mr Alex CHU makes special remarks of a survey vehicle which has been used to facilitate the production of the 3D Digital Map. Installed with a Vehicle-based Mobile Mapping System, the survey vehicle has been used to capture street views and collect data such as locations, heights and exterior features of buildings. The Vehicle-based Mobile Mapping System comprises a 360-degree spherical camera which is mounted atop the vehicle and equipped with six sensors capable of capturing images simultaneously to produce synthesised images of 30 million pixels; three high-definition cameras on each side of the vehicle; and two cameras at the rear of the vehicle primarily for recording ground information such as road maintenance conditions. Also mounted atop the vehicle are a 3D laser scanner, a global navigation satellite system receiver, positioning equipment, etc. The captured pavement conditions are converted into laser point cloud data and 3D images for direct display on the computer for analysis.

With the advance in 3D mapping technologies, the LandsD will continue to introduce the latest technologies when taking forward the development of other 3D digital map products. Meanwhile, the LandsD will also ensure that the 3D maps produced at different stages are mutually compatible and can support a wider range of spatial data applications, so that everyone can better appreciate the convenience a smart city can bring to their daily lives.