Computer vision based travel aid for the blind crossing roads

This paper proposes a method for detecting frontal pedestrian crossings and estimating its length from image data obtained with a single camera as a travel aid for the blind. It is important for the blind to know whether or not a frontal area is a crossing. The existence of a crossing is detected in two steps. In the first step, feature points for a crossing is extracted using Fisher criterion. In the second step, the existence of a crossing is detected by checking on the peoriodicity of white stripes on the road using projective invariants. Next, we propose a method for estimaing crossing length using extracted feature points. From the experimental results for evaluation, it is found that the existence of a crossing is successfully detected for all 173 real images which include 100 images with crossings and 73 images without crossing. The rms error of crossing length estimation for the 100 images is found 2.29m.