3D Laser Mapping has developed a mobile cityscape mapper that captures highly accurate 3D modeling data of buildings and streets. The development is an enhancement to StreetMapper, the vehicle-mounted laser mapping system that is already well proven in terrain and highway mapping.
StreetMapper is a result of a joint venture with German guidance and navigation specialist IGI mbH – a world first that enables highly rapid and accurate 3D laser mapping from a moving vehicle. The latest developments for ‘architectural surveying’ are currently being evaluated with cityscape mapping projects underway with universities in Germany.
StreetMapper uses multiple laser scanners, each with a range of 150m and 80 degree scanning angle. Each scanner performs up to 10,000 measurements per second with a scanning rate up to 100 scans per second. Numerous laser scanners can be used, and can be arranged on the scanner platform to suit different requirements.
The StreetMapper survey vehicle uses well-proven laser scanning technology to capture the position of up to 40,000 3D points per second whilst in motion. The typical positional accuracy is typically 5mm for good GPS conditions and the point-to-point accuracy within the data is 3cm.
“3D cityscapes are increasingly providing city authorities, architects and developers with an invaluable tool to assess the impact of proposed changes to our cities. The computer-generated 3D models allow existing and proposed developments to be viewed from any angle and orientation. This allows anyone to undertake an on-screen walk around or fly through of an area and project planners can add and change developments easily to illustrate the impact on the environment,” explained Dr Graham Hunter, Managing Director of 3D Laser Mapping.
IGI have upgraded their TERRAControl navigation system specially for city modeling applications where there is reduced GPS visibility due to tall buildings. Using a technique called ‘Direct Inertial Aiding’, an inertial navigation system assists the GPS receiver in areas of poor GPS signals. After losing the GPS signal when passing a tall building, the receiver can rapidly lock on to GPS signals again and maintain positional accuracy.
Initial tests have confirmed that typically the GPS receiver will get back to a high positional accuracy 5 seconds faster after losing the signal. The overall result is higher positional accuracy across the whole survey, which has been proven in recent tests in Germany. “This has made a significant impact in minimising one of the greatest problems with dynamic terrestrial surveys in urban areas” says Hunter.
