| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for measuring a step of a manhole inexpensively and safely.SOLUTION: The step measuring method includes a digital image acquisition step S110, a depression angle calculation step S120, a unit length calculation step S130 and a step calculation step S140. In the depression angle calculation step S120, outer and inner peripheries of a frame surface of a manhole or values corresponding to the number of dots of major and minor axes in a digital image with respect to an outer periphery of a lid are determined to calculate a value corresponding to a depression angle at the time of photographing the manhole. In the unit length calculation step S130, on the basis of the value corresponding to the outer periphery and an actual dimension of the manhole, a relationship between a value corresponding to the number of dots and an actual length is calculated. In the step calculation step S140, a value corresponding to the number of bits in a minor axis direction in the digital image of an inner or outer surface of the frame of the manhole is determined and an actual length is calculated using the value corresponding to the depression angle and the relationship between the value corresponding to the number of dots and the actual length. |
