Automatic target detection for vision metrology with using coloured target

Monitoring the movement of the excavated slope beside of the highway is important works in order to prevent disaster, like a land slide, beforehand. For the purpose to measure the displacement of the slope, it is insufficient to measure few number of the target to catch displacement as a surface. Then, recently some research has been done to apply the technique of the close range photogrammetry method by the digital photograph to measure the excavated slope. But it costs too many time to presume the exterior orientation element of the camera and to mark the all target ID in thirty or more Pictures. The method of applying some target group so called 'Coded Target' like as patterned target placement had been examined, but found out the difficulty for applying to measure the slope. Then the solution of using coloured target and to detect of each of them by software had tried. After some experiment, to describe the image data in colour of HSV colour space is found good for colour recognition. The result of field test mentioned, it could be judged that the automatic processing by the coloured target was effective for the underexposure picture (50%) up to proper exposure picture, and it made possible to reduce the 90% of operational time for the work to estimate camera exterior orientation and to get all target position in each picture.