Rotate 180 degrees around, one click automatic scanning, a few minutes later, the shape and texture data collection and synthesis of a Terra Cotta Warriors has been completed. At Northwestern University in Xi'an, the ancient capital, robots are replacing hand-held scanning to draw and preserve precious cultural relics. This kind of robot, called the rapid collection and modeling device for the appearance of cultural relics, was developed by Chinese scientists in one year by using machine vision, manipulator and other technologies. The developer is Xu Yang, a teacher of Northwest University. His doctor graduated from the school of optoelectronics, Beijing University of Aeronautics and Astronautics, and has been engaged in the research of visual measurement technology of rockets and aircraft. He introduced the manipulator technology commonly used in aerospace manufacturing into cultural relics protection. "The main function of the manipulator is to replace manual data collection. The length of the manipulator we use is up to 1.5 meters, which can make the digital collection of cultural relics have the significant advantages of automation and less manual intervention." Xu Yang said. He introduced that the "eyes" of this robot are composed of a structured light 3D scanner and a high-resolution color camera, called the cultural relics appearance data acquisition module. Its mechanical arm is similar to the body, and the large-diameter rotating platform is shaped like two feet. During the collection process, the mechanical arms carrying the cultural relics appearance data collection module are arranged on both sides of the rotating platform, and the complete collection of cultural relics appearance data is realized by rotating 180 degrees around the cultural relics respectively. "The structured light is projected onto the surface of the cultural relics through the fringe projector, and the structured light is decoded with the help of the structured light images taken by two industrial cameras. Combined with the movement of the mechanical arm and the rotation of the turntable, the complete acquisition of the three-dimensional morphology of the surface of the cultural relics is finally completed." Xu Yang said. Compared with manual hand-held scanning, the robot acquisition method avoids interference and even damage to cultural relics. "During the collection process, the cultural relics are placed in the non rotating area in the center of the rotating platform and always remain stationary. The collection module carried by the mechanical arm is photographed at intervals to minimize the interference and damage to the cultural relics." This digital acquisition method significantly improves the acquisition efficiency. "Take a Terra Cotta Warriors as an example. If it is measured and photographed manually, it may take half a day." Xu Yang said, "with the rapid acquisition and modeling device for the appearance of cultural relics developed by us, pressing an automatic scanning key takes about 5 minutes to automatically complete the whole scanning step, and then by pressing an automatic processing button, the three-dimensional data on the surface of cultural relics can be calculated. The whole process is less than 10 minutes, realizing the automatic acquisition and synthesis of cultural relics' shape and texture data." In addition, the improvement of measurement accuracy is also a significant advantage of this technology. "Our sampling density is very high, and the minimum point distance of the point cloud can reach 0.1mm. The collection resolution of texture information will be higher, which can reach 0.05mm. Finally, a 3D model of cultural relics with texture image will be generated. In the virtual environment, we can carry out virtual repair on it." Xu Yang said. At present, this digital collection method will be gradually put into use in institutions such as the National Museum of China. "This will significantly improve the efficiency of digitizing cultural relics in our collection. We plan to develop different series, such as different collection devices for small or large-scale cultural relics, to achieve more efficient collection." Xu Yang said. (Xinhua News Agency)