System Design Concept

 

The high-accuracy GPS/INS/CCD system designed for monitoring linear highway features is based on the concept of the sensor integration, combining post-processing with real-time image processing. The two primary components of the mobile mapping system currently being implemented are precise navigation and digital imaging, both allow for flexible and optimal system design, leading potentially to near-real time overall data processing. The navigation component, in essence, follows the structure of the AIMSÔ system, developed earlier at the Center for Mapping, OSU. The imaging system provides the connection between the high-precision vehicle navigation data and the marks on the road surface. For economic reasons, the processing of the images must be automated, preferably performed in real-time. Figure 1 shows the concept of the centerline mapping system.

 

 

 

 

 

 

 

 

 

 

 

 

 

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Figure 1. Sensor geometry of the mapping system.

 

Under ideal conditions, the centerline offset from the vehicle position can be easily obtained from monoscopical image measurements, provided the vehicle geometry and the camera model are known. Vehicle position/attitude changes due to its motion and road unevenness introduce at the same time non-negligible errors in this model. To compensate for these errors, a stereo technique can be used, which can be easily achieved by acquiring overlapped imagery. Since a single camera collects images, the stereovision is realized by the platform motion, which, in turn, emphasizes the need for high-precision sensor orientation.