Detailed Facade Reconstruction for Mahattan-world Buildings

Abstract

3D building models play an important role in many real-world applications. Different models are suitable for different application scenarios based on their levels of detail. LOD3 models with facade details are crucial for many applications, such as virtual reality and urban simulation. Currently, 3D building models with lower LOD are largely available, but the number of LOD3 models is very limited. Most LOD3 reconstruction methods depend on manual operation, which is very time-consuming. How to automatically reconstruct the detailed facade for building models has remained a problem in computer vision. The problem can be seen as an image processing problem, but how to convert the 2D results into 3D smoothly should also be considered.  In this project, we proposed a method to automatically reconstruct the detailed building models based on the Faster R-CNN. The method starts from a set of street view images, and the results are models with facade elements. A 3D point cloud can be extracted from the images using SfM and MVS, and the camera parameters can also be recovered. We take advantage of the high-quality facade images and parse the facades to detect their bounding boxes. The bounding boxes can match pretty well with the rectangular shape of the facade elements. The 2D facade elements can be added to the 3D building model based on the camera parameters. The process is very efficient and automatic. The regularity of the facade elements will be reserved, making the result more convincing. Our method includes four main steps:  (1) coarse model reconstruction, (2) facade image selection and rectification, (3) facade element detection and regularization, and (4) detailed facade reconstruction. Experiment results show that our method can produce reliable building models with facade details for many different situations. It can work for both the multi-face building blocks and the street side buildings. Our test shows that the window detection performance is pretty good. The object detection is extremely fast, and the whole pipeline is lightweight and efficient. In theory, the method can also be extended to reconstruct large-scale city models, which means it has broad application prospects.