| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to easily acquire a gradation of a road surface without considering a displacement of a spring upper part.SOLUTION: An illumination device is configured to emits parallel light beams B1 and B2. The parallel beams B1 and B2 hit a road surface to form marks Pc1 and Pc2, and an imaging object including the marks Pc1 and Pc2 is photographed by an imaging device to obtain an imaging image J. An interval e in a vertical direction between marks Mc1 and Mc2 corresponding to the marks Pc1 and Pc2 is detected. On one hand, in a gradation determination table storage unit, a relation between the interval e and a gradation γ is stored. On the basis of the relation and the interval e between the two mark images, the gradation γ is acquired. Even when a spring upper part on which the illumination device and the imaging device are provided changes in height, a relative position relation between the two mark images stays the same if the gradation of the road surface is the same. Therefore, the gradation of the road surface can be acquired without considering a displacement of the spring upper part.SELECTED DRAWING: Figure 1 |
