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LangSplat: 3D Language Gaussian Splatting
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Builds a 3D language field by attaching SAM-hierarchy CLIP features to 3D Gaussians compressed via a scene-specific autoencoder, enabling fast open-vocabulary 3D querying.
Problem
Existing 3D language fields built on NeRF with CLIP features are slow to render and produce imprecise, vague object boundaries, and need multi-scale patch querying at inference.
Approach
Replace NeRF with 3D Gaussian Splatting carrying language embeddings, supervise with CLIP features from SAM masks at three semantic levels (subpart/part/whole) instead of multi-scale patches or DINO regularization, and learn in a low-dimensional scene-specific latent space via an autoencoder.
Key results
- LangSplat reaches 84.3% overall localization accuracy on the LERF dataset versus 73.6% for LERF.
- LangSplat achieves 93.4% overall mIoU on 3D-OVS, versus 86.8% for the prior 3D-OVS method.
- LangSplat is 199x faster than LERF per text query at 1440x1080 resolution on an RTX-3090.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use LangSplat instead of LERF | 3D object localization · LERF dataset (overall) | localization accuracy (%): 73.6 -> 84.3 | Helped |
| Use LangSplat instead of LERF | 3D semantic segmentation · LERF dataset (overall) | IoU (%): 37.4 -> 51.4 | Helped |
| Use LangSplat instead of 3D-OVS | 3D semantic segmentation · 3D-OVS dataset (overall) | mIoU (%): 86.8 -> 93.4 | Helped |
| Add SAM-based hierarchical semantics (ablation) | LangSplat · ramen scene | IoU (%): 28.20 -> 46.74 | Helped |
| Add SAM-based hierarchical semantics (ablation) | LangSplat · 3D-OVS bench scene | mIoU (%): 53.2 -> 85.7 | Helped |
| Add scene-specific autoencoder and 3D Gaussian Splatting (ablation) | LangSplat with SAM · ramen scene | IoU (%): 46.74 -> 51.15 | Helped |
| Add scene-specific autoencoder and 3D Gaussian Splatting (ablation) | LangSplat with SAM · 3D-OVS bench scene | mIoU (%): 85.7 -> 94.2 | Helped |
| Remove SAM-based hierarchical semantics while retaining AE and 3D-GS (ablation) | LangSplat · ramen scene | IoU (%) | Hurt |
| Remove SAM-based hierarchical semantics while retaining AE and 3D-GS (ablation) | LangSplat · 3D-OVS bench scene | mIoU (%) | Hurt |
Surprising findings
- Naively replacing NeRF with 3D Gaussian Splatting while storing full 512-dimensional CLIP features runs out of memory, so the autoencoder is required.
Limitations
- Decoder dominates query time; the authors suggest a 1x1 convolution replacement for speed but do not implement it.
- Per-scene optimization is required, and the method is not generalized across scenes.
Experimental setup
Datasets: LERF dataset 3D-OVS dataset
Benchmarks: LERF dataset 3D-OVS dataset
Metrics: localization accuracy IoU mIoU query speed (s/query)
Baselines: LERF LSeg 3D-OVS ODISE OV-Seg FFD
Builds on: 3D Gaussian Splatting LERF Segment Anything CLIP
Closest papers by meaning
- LangSplatV2: High-dimensional 3D Language Gaussian Splatting with 450+ FPS (NeurIPS 2025 · similarity 0.93)
- Language Embedded 3D Gaussians for Open-Vocabulary Scene Understanding (CVPR 2024 · similarity 0.91)
- Dr. Splat: Directly Referring 3D Gaussian Splatting via Direct Language Embedding Registration (CVPR 2025 · similarity 0.91)
- SceneSplat++: A Large Dataset and Comprehensive Benchmark for Language Gaussian Splatting (NeurIPS 2025 · similarity 0.91)
- 4D LangSplat: 4D Language Gaussian Splatting via Multimodal Large Language Models (CVPR 2025 · similarity 0.91)
- SOVGaussian: Sparse-View 3D Gaussian Splatting for Open-Vocabulary Scene Understanding (AAAI 2025 · similarity 0.91)
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