2014 Volume 70 Issue 4 Pages 211-226
This paper presents a novel method that automatically extracts regions and tracks of vehicles from traffic video images observed even when local sunlight condition varies or at nighttime. The proposed method first generates “accumulated temporal subtraction images” by accumulating temporal subtraction images within a certain period, and removes shadows by counting the number of brightness change in the images. This process removes parts of vehicles, but the lacking parts are compensated by accumulating the accumulated temporal subtraction images after removing shadow. As a result, the vehicle's track is determined. Then, the vehicle region at a certain time is delineated by multiplying the track without shadow and a tentative vehicle region with shadow. Finally, the image is converted into bird-eye view images, and the velocity of a vehicle is estimated by subtracting vehicle's positions shown in two bird-eye view images. We applied the method to traffic video images observed in Kyoto, and it was found that F-value was 0.98, and accordingly the proposed method performs very accurately.