The development of BIM technology has promoted a new revolution in the construction industry. With the deepening concepts of green buildings, intelligent buildings and urban sustainable development, the existing modeling methods can no longer meet the latest modeling requirements. In recent years, 3D real-time modeling technology has been widely used in model reconstruction of existing buildings. Thus, how to realize high-precision, fast-rate, low-cost real-life modeling becomes an important problem faced by numerous technicians. This paper uses the tilt photography technology to realize 3D real-world modeling. Based on an actual engineering case study, an implementable reference plan is proposed, and the real-world modeling method is used to monitor the settlement of the tunnel entrance.