Detection method and system of building surface defects

The invention provides a detection method and system of building surface defects. The method comprises the following steps: according to the rectangular coordinates of at least two target points on a building under a first erection coordinate system and the world coordinates of the at least two target points on the building under a world coordinate system, determining a first mapping relationship, positioning the first defect of the building surface, and obtaining the image information of the first defect and the rectangular coordinate under the first erection coordinate system, wherein the first mapping relationship is the mapping relationship between the rectangular coordinate of any point in space under the first erection coordinate system and the world coordinate of any point in space under the world coordinate system; according to the rectangular coordinate of the first defect under the first erection coordinate system and the first mapping relationship, determining the world coordinate of the first defect; and according to the rectangular coordinate of the first defect under the first erection coordinate system and the image information of the first defect, determining the practical dimension information of the first defect. The automatic detection method of the defects on the basis of positioning saves time and labor so as to improve defect defection efficiency.