The utilization of 3D digital technology in urban sculptures has led to the development of modern urban sculptures. With the constant developments in computer technology, the combination presents a broad scope of exploration, with a wide array of applications. This paper details the process involved in combining 3D digital technology in the making of urban sculptures, presenting two methods geared towards attaining an organic integration of the two technologies. Processing point cloud acquisition scanning algorithms, determining robotic scanning step distances, and preprocessing point cloud data information. Applying gradient calculation methods to the process of decomposing feature points for restructuring the edge contours of the point images of sculptures. Applying the Sigma model to the continuous 3D point cloud reconstruction of sparse point images and developing an automatic 3D reconstruction algorithm for sparse point clouds of sculptures. Analyzing the time complexity of the automatic 3D reconstruction algorithm and its application in the reconstruction of the urban volcano sculpture. This technique can extract point cloud data constrained by features from coffee cup models, plant pot models, gear models, and Einstein head busts, capture important features, and complete the 3D reconstruction of the urban volcano sculpture.
