High-Precision Integrated GPS/INS/CCD System for Transportation Applications

Abstract

The Ohio State University currently is developing a GPS/INS/CCD integrated system(1) for precise (centimeter level) monitoring of highway center and edge lines. The positioning component of the system is based on a tightly integrated GPS/INS system, and the imaging component comprises a single down-looking, high-performance digital color camera. The high image rate provides sufficient overlap of the subsequent images at highway speed; therefore, stereo data processing is expected to be performed in real-time with the support of on-the-fly navigation solution. From the navigation standpoint, post processing of GPS/INS data provides more accurate orientation, a benefit of forward and backward trajectory processing, and precisely synchronized timing information. However, approximate navigation data available in real-time (e.g., the estimates of the motion between epochs, when consecutive images are taken, can provide camera orientation and especially the relative orientation estimates) can be used to support image matching on-the-fly, necessitating extracting and storing only the needed information, as opposed to the entire image (we are only concerned with simple linear features). Besides the motion, the attitude change between two image captures is of interest, since the quality of these estimates has a very strong impact on the search space, allowing for short computation times and making the whole concept feasible in real-time. Obviously, additional post-processing will further refine the positioning and orientation data extracted in real-time and will provide precise geo-referencing of the features. The technique of using navigation data to support OTF image processing adds more robustness to the system, allowing faster and more automatic data processing and saves storage space and processing time, because data acquisition is combined, with the image pre-processing.