As digital twins become central to the transformation of modern cities, accurate and structured 3D building models emerge as a key enabler of high-fidelity, updatable urban representations. These models underpin diverse applications including energy modeling, urban planning, autonomous navigation, and real-time reasoning. Despite recent advances in 3D urban modeling, most learning-based models are trained on building datasets with limited architectural diversity, which significantly undermines their generalizability across heterogeneous urban environments. To address this limitation, we present BuildingWorld, a comprehensive and structured 3D building dataset designed to bridge the gap in stylistic diversity. It encompasses buildings from geographically and architecturally diverse regions—including North America, Europe, Asia, Africa, and Oceania—offering a globally representative dataset for urban-scale foundation modeling and analysis. Specifically, BuildingWorld provides about Five million LOD2 building models collected from diverse sources, accompanied by both real and simulated airborne LiDAR point clouds. This enables comprehensive research on 3D reconstruction, building detection and segmentation, as well as roof structure segmentation. Cyber City, a virtual city model, is introduced to enable the generation of unlimited training data with customized and structurally diverse point cloud distributions. Furthermore, we provide standardized evaluation metrics tailored for building reconstruction, aiming to facilitate the training, evaluation, and comparison of large-scale vision models and foundation models in structured 3D urban environments

Building reconstruction is a challenging problem at the intersection of computer vision, photogrammetry and computer graphics. 3D wireframe presents a compelling representation for building modeling through its compact structure. Existing wireframe reconstruction methods employing vertex detection and edge regression have achieved promising results. In this paper, we develop an Edge-aware Diffusion network, dubbed EdgeDiff. As a novel paradigm for wireframe reconstruction, the EdgeDiff generates wireframe models from noise using a conditional diffusion model. During the training process, the ground truth wireframes firstly are formulated as a set of parameterized edges and then diffused into a random noise distribution. EdgeDiff learns both the noise reversal process and the network structure simultaneously. During inference, EdgeDiff iteratively refines the generated edge distribution using the denoising diffusion implicit model, enabling flexible single- or multi-step denoising and dynamic adaptation to buildings of varying complexity. Additionally, given the unique structure of wireframes, we introduce an edge attention module to extract point-wise attention from point features, using it as auxiliary information to facilitate learning of edge cues and guide the network toward improved edge awareness. Extensive experiments on the real-world Building3D dataset demonstrate that our approach achieves state-of-the-art performance.

In this paper, we present BWFormer, a novel Transformerbased model for building wireframe reconstruction from airborne LiDAR point cloud. The problem is solved in a ground-up manner here by detecting the building corners in 2D, lifting and connecting them in 3D space afterwards with additional data augmentation. Due to the 2.5D characteristic of the airborne LiDAR point cloud, we simplify the problem by projecting the points on the ground plane to produce a 2D height map. With the height map, a heat map is first generated with pixel-wise corner likelihood to predict the possible 2D corners. Then, 3D corners are predicted by a Transformer-based network with extra height embedding initialization. This 2D-to-3D corner detection strategy reduces the search space significantly. To recover the topological connections among the corners, edges are finally predicted from the height map with the proposed edge attention mechanism, which extracts holistic features and preserves local details simultaneously. In addition, due to the limited datasets in the field and the irregularity of the point clouds, a conditional latent diffusion model for LiDAR scanning simulation is utilized for data augmentation. BW-Former surpasses other state-of-the-art methods, especially in reconstruction completeness. Our code is available at: https : //github.com/3dv-casia/BWformer/.

Roof wireframe reconstruction has shown great success in 3D building reconstruction due to its lightweight nature and straightforward representation. However, previous methods consider all roof points, which result in edge redundancy and omissions. In this paper, we propose a novel and streamlined Edge-guided Geometric wireframe reconstruction framework, named EDGE. We find that points distributed along the roof edges make a significant contribution to the precise geometric structure of wireframe. Therefore, we design an edge point extractor (EPE) to capture the spatial relationship between points and edges, filtering out internal plane points. Moreover, we discover that the previous edge detectors rely solely on corner points, leading to error accumulation. To address this, we present the Hybrid Edge Detector (HED) feeding corner points with edge contextual features, which not only enhances edge completeness but also mitigates edge redundancy. Comprehensive experiments demonstrate EDGE outperforms existing wireframe reconstruction methods with 0.86 Corner F1-score and 0.71 Edge F1-score on Building3D dataset, striking the significant improvement of accuracy between corner and edge. Notably, our EDGE achieves a significant improvement of over 11% in Edge Recall, demonstrating the effectiveness and robustness of the proposed method.

In this paper, we present an end-to-end 3D-building-wireframe reconstruction method to regress edges directly from aerial light-detection-and-ranging (LiDAR) point clouds. Our method, named parametric-building-wireframe reconstruction (PBWR), takes aerial LiDAR point clouds and initial edge entities as input and fully uses the self-attention mechanism of transformers to regress edge parameters without any intermediate steps such as corner prediction. We propose an edge non-maximum suppression (E-NMS) module based on edge similarity to remove redundant edges. Additionally, a dedicated edge loss function is utilized to guide the PBWR in regressing edges parameters when the simple use of the edge distance loss is not suitable. In our experiments, our proposed method demonstrated state-of-the-art results on the Building3D dataset, achieving an improvement of approximately 36% in Entry-level dataset edge accuracy and around a 42% improvement in the Tallinn dataset.

This study introduces an efficient approach for clustering roof wireframe vertices within the realm of model simplification based on a multiclass twin support vector machine (TWSVM) framework. The proposed method first assigns a dynamic label to each point of the input point cloud, and it then iteratively identifies k cluster center 3-D lines by maintaining short distances between wireframe candidate vertices sharing the same corner. In addition, it ensures that these wireframe candidates from one corner are distanced from the wireframe vertices from the other corners in a drafting roof dataset. This study extends the multiclass TWSVM to tackle the clustering problem of roof wireframe vertices, thus facilitating model simplification. Remarkably, this problem can be solved using a straightforward and efficient iterative algorithm. The results demonstrate that our proposed method achieves more accurate clustering results on 20 out of 24 roof wireframe vertex datasets compared with other relevant methods. Furthermore, the proposed method can efficiently and accurately extract the majority of vertices from roof wireframes in real-world Building3D dataset.

Reconstructing building roofs from light detection and ranging (LiDAR) point clouds from aerial perspectives is significantly important in photogrammetry domains. This letter proposes a novel approach for three-dimensional (3D) real-world building roof reconstruction in Estonia, employing a two-stage self-supervised pre-training architecture to transform 3D roof point clouds into wireframe models. We utilize a self-supervised pre-training framework that incorporates a purpose-designed and efficient self-attention mechanism to generate point-wise features. Subsequently, we develop modules for corner detection and edge prediction to classify and regress the coordinates of corner points and determine optimal edge selections, respectively, to construct the final wireframe model. The effectiveness of our approach is evaluated on real-world roof datasets, achieving corner and edge precision accuracies of 83% and 78%, respectively. In addition, fine-tuning our self-supervised pre-training method with varying ratios of labeled data, particularly with only 50% partially labeled data, attains superior performance, achieving 84% and 85% corner and edge precision, respectively.

Urban modeling from LiDAR point clouds is an important topic in computer vision, computer graphics, photogrammetry and remote sensing. 3D city models have found a wide range of applications in smart cities, autonomous navigation, urban planning and mapping etc. However, existing datasets for 3D modeling mainly focus on common objects such as furniture or cars. Lack of building datasets has become a major obstacle for applying deep learning technology to specific domains such as urban modeling. In this paper, we present an urban-scale dataset consisting of more than 160 thousands buildings along with corresponding point clouds, mesh and wireframe models, covering 16 cities in Estonia about 998 Km2. We extensively evaluate performance of state-of-the-art algorithms including handcrafted and deep feature based methods. Experimental results indicate that Building3D has challenges of high intra-class variance, data imbalance and large-scale noises. The Building3D is the first and largest urban-scale building modeling benchmark, allowing a comparison of supervised and self-supervised learning methods. We believe that our Building3D will facilitate future research on urban modeling, aerial path planning, mesh simplification, and semantic/part segmentation etc.

One-stage 3D object detection using mobile light detection and ranging (LiDAR) has developed rapidly in recent years. Specifically, one-stage methods have attracted attention because of their high efficiency and light weight compared with two-stage methods. Inspired by this, we present the semantic segmentation assisted one-stage three-dimensional vehicle object detection (SSA3D), a network for the rapid detection of objects that keeps the advantages of the semantic segmentation module in the two-stage methods without increasing redundant computational load. First, we modified the sampling of the farthest point to improve the quality of the sampling points. This helps to reduce sampling outlier points and bad points that are difficult to perceive in the spatial structure information surrounding the point. Second, a neighbor attention group module is devoted to selectively add extra weight to neighbor points because of the different importance of neighbor points for the corresponding sampling point. Correctly increasing the weight is helpful to obtain richer spatial structure information. Finally, a delicate box generation module is included as a voted center point layer based on the generalized Hoff vote method and an anchor-free regression. We used the feature aggregation module as the backbone and the feature propagation module as the auxiliary network to achieve efficiency. At the same time, the auxiliary network retains the ability to extract point-wise features from the state-of-the-art semantic segmentation network. In experiments, we evaluated and tested the SSA3D on a common KITTI dataset and achieved improved performance in the class of car accuracy.