PartNet: A Large-scale Benchmark for Fine-grained and Hierarchical Part-level 3D Object Understanding

Kaichun Mo1     Shilin Zhu2     Angel X. Chang3     Li Yi1    
Subarna Tripathi4     Leonidas J. Guibas1     Hao Su2    

1 Stanford University     2 University of California San Diego    
3 Simon Fraser University     4 Intel AI Lab

[ArXiv Preprint (Low-res)] [BibTex] [Code (Github)]
[Paper (High-res, 6.8M)] [Supplementary Materials (High-res, 25M)]
[Data (Stay Tuned)] [Online Benchmark (Stay Tuned)]

We present PartNet: a consistent, large-scale dataset of 3D objects annotated with fine-grained, instance-level, and hierarchical 3D part information. Our dataset consists of 573,585 part instances over 26,671 3D models covering 24 object categories. This dataset enables and serves as a catalyst for many tasks such as shape analysis, dynamic 3D scene modeling and simulation, affordance analysis, and others. Using our dataset, we establish three benchmarking tasks for evaluating 3D part recognition: fine-grained semantic segmentation, hierarchical semantic segmentation, and instance segmentation. We benchmark four state-of-the-art 3D deep learning algorithms for fine-grained semantic segmentation and three baseline methods for hierarchical semantic segmentation. We also propose a novel method for part instance segmentation and demonstrate its superior performance over existing methods.

Dataset Visualization

Figure 1. PartNet Dataset and Three Benchmarking Tasks. Left: we show example annotations at three levels of segmentation in the hierarchy. Right: we propose three fundamental and challenging segmentation tasks and establish benchmarks using PartNet.

Figure 2. PartNet Fine-grained Instance-level Shape Part Annotation. We visualize example shapes with fine-grained part annotations for the 24 object categories in PartNet.

Figure 3. PartNet Hierarchical Shape Part Template and Annotation. We show the expert-defined hierarchical template for lamp (middle) and the instantiations for a table lamp (left) and a ceiling lamp(right). The And-nodes are drawn in solid lines and Or-nodes in dash lines. The template is deep and comprehensive to cover structurallydifferent types of lamps. In the meantime, the same part concepts, such as light bulb and lamp shade, are shared across the different types.

Data Annotation

Figure 4. Data Annotation Workflow. We show our annotation interface with its components, the proposed question-answering workflow and the mesh cutting interface.

A Novel Method for Part Instance Segmentation

Figure 5. The Proposed Method for Part Instance Segmentation. The network learns to predict three components: the semantic label for each point, a set of disjoint instance masks and their confidence scores for part instances.

Figure 6. Qualitative Comparison To SGPN. We show qualitative comparisons for our proposed method and SGPN. Our method produces more robust and cleaner results than SGPN.

Figure 7. Learned Part Instance Correspondences. Our proposed method learns structural priors within each object category that is more instance-aware and robust in predicting complete instances. We observe that training for a set of disjoint masks across multiple shapes gives us consistent part instances. The corresponding parts are marked with the same color.


This research was supported by NSF grants CRI-1729205 and IIS-1763268, a Vannevar Bush Faculty Fellowship, a Google fellowship, and gifts from Autodesk, Google and Intel AI Lab. We especially thank Zhe Hu from Hikvision for the help on data annotation and Linfeng Zhao for the help on preparing hierarchical templates. We appreciate the 66 annotators from Hikvision, Ytuuu and Data++ on data annotation. We also thank Ellen Blaine for helping with the narration of the video.