Abstract: The protection of ancient buildings is a hot research topic in the field of surveying and mapping. Non-contact measurement is a powerful measure to overcome the lack of digitalization of traditional methods and easily cause "secondary damage". Taking the aliens of No. 99 Hongxia street in Harbin as an example, this paper proposes a research project of combining 3D laser scanning technology with UAV aerial survey technology to reconstruct ancient buildings. Based on the point cloud data and image data of the ancient building acquired by the 3D laser scanner and the drone, the point cloud data is used to generate the orthophoto image and the flat, vertical, and sectional images are created, and the 3D model is created, and finally the building is measured in the field. Dimensional data is a reference analysis that yields drawing and model errors. The results show that the 3D laser point cloud combined with the UAV image can efficiently restore the architectural drawings and create a high-precision and refined 3D model, which provides a new thinking mode for the protection of ancient buildings.

Key words: 3D laser scanning, point cloud, drone image, three-dimensional model, reconstruction