LBS in 3D

Chen Ruizhi, Zhang Jixian, Jarmo Takala and Wang Jianyu
09 Jun 2010
00:00

Modeling methods are developed to meet the application requirements of personal navigation: small model size, high accuracy, and good visual appearance. Small model size is achieved by simplified object geometry and reduced texture resolution. Model accuracy is controlled by extracting building outlines from a classified point cloud and overlapping with the final 3D model. The model completeness is checked by comparing the resulting model with original images. Good visual effect is realized by applying photo-realistic texture. Photo-realistic texture provides rich information for the 3D scene reconstructed. Only the individual object texture and the final model constructions require manual editing.

To import the final 3D models to a mobile phone, the size of an individual model is restricted to less than 100 kb. To optimize model size, a row of buildings is divided into several building blocks.
 
Multi-sensor positioning

As long as open-sky satellite-signal conditions are available, there are no problems to locate a mobile user with the built-in GPS receiver of a smartphone with a positioning accuracy of a few meters. However, most popular location-based services occur in GNSS-degraded environments such as in indoor environments and urban canyons. Locating a mobile user seamlessly any time anywhere under any circumstance is still a very challenging task, especially to implement such an indoor/outdoor positioning solution in a DSP platform.

FGI is now developing a DSP-based multi-sensor positioning platform to approach a seamless indoor/outdoor locating solution. The platform consists of a GPS module, a 3D accelerometer, and a 2D digital compass. A DSP is embedded in the GPS module. All sensors are integrated to the DSP that hosts a core software for real-time sensor data acquisition and real-time processing to estimate user's location.

The multi-sensor platform provides opportunities to investigate the positioning solutions with a GPS/Reduced-INS (Inertial Navigation System) combination or GPS/PDR (Pedestrian Dead Reckoning) combination. The Reduced-INS combination is defined as a combination of a 3D accelerometer and a 2D digital compass, and is a very low-cost approach of sensor augmentation. The GPS/Reduced-INS implementation is implemented in a loosely coupled Kalman filter, while the GPS/PDR algorithm is based on pedestrian-targeted dead reckoning, with heading error and step length estimation methodology.

Try it in Shanghai

The prototype system has so far met these challenges: the high performance required of real-time 3D visualization in a smartphone; high positioning availability with acceptable accuracy in indoor and outdoor environments; and the demanding requirements of the 3D models for a small phone, including small model size, high accuracy, and good visual appearance.

Meanwhile, the prototype is being tested and demonstrated at the 2010 World Expo in Shanghai, implemented with a smartphone software package: anyone with a Nokia phone (S60 with built-in GPS and Wi-Fi/Bluetooth) can experience the 3D personal navigation and LBS service in the Expo area by downloading and installing the 3D models.

Chen Ruizhi is a professor and head of the Department of Navigation and Positioning at the Finnish Geodetic Institute.

Zhang Jixian is a professor and president of the Chinese Academy of Surveying and Mapping.

Jarmo Takala is a professor and head of the Department of Computer Systems at Tampere University of Technology in Finland.

Wang Jianyu is a professor at the Shanghai Institute of Technical Physics, Chinese Academy of Sciences.

This article originally appeared in GPS World
 

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