The invention belongs to the technical field of 
visual detection, and discloses a method for measuring the seat posture of a hob cutter of a 
shield machine based on 
monocular vision.  S1 knows the three-dimensional model of the 
tool holder and the calibration results of the camera. Through the camera 
projection model, the world coordinates of the corner points of the 
tool holder in different poses are converted into image coordinates, and the image coordinates of the corner points under each 
pose are stored to form the tool.  Seat posture 
template library; S2 collects the actual image of the 
tool holder to be measured and performs 
image processing to obtain the coordinates of the corner points in the actual image and the chamfering distance transformation map of the 
binary image containing only the corner points; S3 through the chamfering distance transformation map  , calculate the distance feature value between each template in the 
pose library and the actual tool seat, and use the template 
pose corresponding to the 
minimum distance feature value as the estimated pose of the tool seat to achieve accurate positioning of the tool seat; through the present invention, the tool seat pose 
estimation accuracy  high and computationally efficient.