SemanticKITTI: A Dataset for Semantic Scene Understanding of LiDAR Sequences
Jens BehleyMartin GarbadeAndres MiliotoJan QuenzelSven BehnkeCyrill StachnissJuergen Gall
Introduces SemanticKITTI, a large-scale dataset providing dense, point-wise 360-degree semantic annotations for LiDAR sequences from the KITTI benchmark alongside standard baseline tasks for single-scan segmentation, multi-scan segmentation, and semantic scene completion in autonomous driving.
Self-driving cars require detailed understanding of their surroundings to navigate safely, but existing datasets for semantic segmentation of LiDAR point clouds remain small and lack sequential information from automotive sensors. This gap hinders development of methods that can handle real-world driving scenarios, including changes in the environment and unmapped areas.
The article introduces SemanticKITTI, a large annotated dataset derived from the KITTI Odometry Benchmark, to support three tasks: semantic segmentation from single scans, segmentation from multiple past scans, and semantic scene completion that predicts future scene structure.
Researchers annotated over 43,000 scans across 22 sequences with 28 classes using a custom labeling tool that aggregates scans via SLAM for consistency. They evaluated multiple state-of-the-art point cloud segmentation methods as baselines on the training and test splits.
The best single-scan method achieved 49.9% mean intersection-over-union across 19 classes, with performance declining sharply at greater distances due to sparsity. Multi-scan approaches showed limited gains in distinguishing moving from static objects. Semantic scene completion reached 50.6% completion IoU and 17.7% semantic mIoU only when using a higher-resolution backbone.
These results indicate that current models lack sufficient capacity and mechanisms to exploit temporal data or handle sparse distant points effectively, which limits reliable perception for autonomous driving. The dataset enables reproducible progress and new directions such as semantic SLAM.
Future work should develop architectures that process sequential inputs more explicitly and produce higher-resolution outputs. Instance-level annotations over time are planned to support additional tasks.
The findings rest on a single sensor type and location, with class imbalance and limited test evaluations that may affect generalization; results should be validated on diverse environments before deployment decisions.
- Paper: The Cityscapes Dataset for Semantic Urban Scene Understanding, Marius Cordts et al. (2016). Cityscapes establishes the foundational urban street scene segmentation benchmark, class taxonomy, and evaluation protocols that SemanticKITTI translates to sequential automotive LiDAR.
- Paper: Fully convolutional networks for semantic segmentation, Jonathan Long et al. (2015). This seminal work introduced end-to-end fully convolutional networks for semantic segmentation, providing the foundational architectural paradigm for the 2D projection and volumetric baselines evaluated in SemanticKITTI.
- Paper: VoxelNet: End-to-End Learning for Point Cloud Based 3D Object Detection, Yin Zhou et al. (2017). VoxelNet introduced end-to-end learning directly from sparse LiDAR point clouds using voxel feature encoding, establishing the key volumetric representation utilized for SemanticKITTI's baseline models.
- Paper: ScanNet: Richly-Annotated 3D Reconstructions of Indoor Scenes, Angela Dai et al. (2017). ScanNet pioneered large-scale richly annotated 3D volumetric segmentation and scene completion benchmarks, directly motivating SemanticKITTI's expansion of 3D semantic tasks to outdoor driving environments.
- Paper: Object scene flow for autonomous vehicles, Moritz Menze et al. (2015). This paper establishes dynamic 3D scene flow on the KITTI dataset, laying the groundwork for interpreting dynamic vs. static objects in autonomous driving sequences.
- Paper: Multi-view 3D Object Detection Network for Autonomous Driving, Xiaozhi Chen et al. (2017). MV3D provides essential background on utilizing multi-view bird's-eye and front-view representations for processing LiDAR point clouds on the KITTI benchmark.
- Paper: SUN RGB-D: A RGB-D scene understanding benchmark suite, Shuran Song et al. (2015). SUN RGB-D formulated core benchmarking methodologies and metrics for dense 3D semantic scene understanding that precede outdoor LiDAR evaluation suites.
- Paper: RandLA-Net: Efficient Semantic Segmentation of Large-Scale Point Clouds, Qingyong Hu et al. (2019). RandLA-Net directly addresses the scalability and efficiency bottlenecks highlighted by SemanticKITTI by benchmarking a lightweight, point-based architecture on SemanticKITTI's large-scale point clouds.
- Paper: 4D Spatio-Temporal ConvNets: Minkowski Convolutional Neural Networks, Christopher Choy et al. (2019). This paper introduces 4D spatio-temporal sparse convolutions (Minkowski Engine) to efficiently process sequential 3D scans over time, fulfilling the core temporal modeling need identified in SemanticKITTI.
- Paper: Deep Learning for 3D Point Clouds: A Survey, Yulan Guo et al. (2019). This survey provides a comprehensive synthesis of deep learning methods for 3D point cloud segmentation and scene understanding, situating SemanticKITTI within the broader landscape of 3D benchmarks.
- Paper: nuScenes: A Multimodal Dataset for Autonomous Driving, Holger Caesar et al. (2019). nuScenes extends multimodal autonomous driving benchmarks beyond KITTI by capturing multi-sweep LiDAR alongside synchronized 360-degree cameras and radar in adverse weather and night conditions.
- Paper: Scalability in Perception for Autonomous Driving: Waymo Open Dataset, Pei Sun et al. (2019). Waymo Open Dataset scales sequential LiDAR perception to massive multi-city environments with rich temporal sequences, building upon the sequential LiDAR benchmark formulations of SemanticKITTI.
- Paper: BDD100K: A Diverse Driving Dataset for Heterogeneous Multitask Learning, Fisher Yu et al. (2020). BDD100K broadens the multitask driving perception agenda to diverse heterogeneous driving scenarios across geographic domains.
