Urban concealed culvert trend continuous tracking method

An urban concealed culvert trend continuous tracking method comprises the following steps: S1, determining at least one concealed culvert exposed point or known point, and measuring the space coordinates of the exposed point or known point; s2, drilling three-dimensional laser measurement is carried out at the exposed point or the known point, point cloud coordinate information in the buried culvert within the effective drilling three-dimensional laser detection range is calculated through the exposed point or the known point, and a point cloud coordinate set of the section where the drilling hole is located is obtained; s3, through the point cloud coordinate set in the step S2, a three-dimensional model of the section where the drilled hole is located in the buried culvert is built; s4, identifying a discharge port in the buried culvert through the three-dimensional model established in the step S2, reading coordinate information of the discharge port, determining a projection position of the discharge port