GeoPurify: A Data-Efficient Geometric Distillation Framework for Open-Vocabulary 3D Segmentation

🎉 Accepted to ICLR 2026 🎉

Weijia Dou¹, Xu Zhang², Yi Bin^1*, Jian Liu³, Bo Peng², Guoqing Wang³, Yang Yang³, Heng Tao Shen¹ (*Corresponding author)

¹Tongji University    ²Tianjin University    ³University of Electronic Science and Technology of China

This is the official repository for GeoPurify. Our work tackles a key challenge in open-vocabulary 3D segmentation: the noisy and fragmented results produced when lifting features from 2D Vision-Language Models (VLMs) to 3D space.

GeoPurify introduces a framework that learns to purify these semantically-rich but geometrically-inconsistent 3D features. By distilling robust, class-agnostic geometric priors from a 3D self-supervised model, it effectively reconciles 2D semantics with 3D structure—all without needing any 3D semantic labels for its training.

Our key novelty in a sentence: GeoPurify achieves state-of-the-art open-vocabulary 3D segmentation with only ~1.5% of training data by learning to purify noisy 2D VLM features using distilled 3D geometric priors.

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📝 Contents

• GeoPurify: A Data-Efficient Geometric Distillation Framework for Open-Vocabulary 3D Segmentation
  • 📝 Contents
  • 🧠 Method Overview
  • ✨ Key Features
  • 🛠️ Installation
  • 🚀 Usage
    • Data Preparation
    • Training GeoPurify
    • Inference
  • 📊 Evaluation
    • Datasets
    • Metrics
    • Results
  • 📦 Checkpoints
    • Usage
  • 📚 Citation
  • 🙏 Acknowledgements
  • 📜 License

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🧠 Method Overview

Our method explicitly decouples semantics and geometry into a two-stage pipeline:

• Stage 1: Training (Geometric Distillation) A sparse 3D Student Affinity Network (φ_S) is trained to comprehend 3D structure. It learns geometric relationships directly from the point cloud by using contrastive distillation to mimic the embeddings of a powerful, frozen 3D SSL teacher (φ_T, e.g., Sonata). Crucially, this training phase requires no 3D semantic labels.
• Stage 2: Inference (Geometry-Guided Pooling) A frozen generalist 2D VLM (Ψ_2D, e.g., X-Decoder) generates initial 3D features by projecting rich semantic content from multi-view images. Because these features are geometrically inconsistent, our pre-trained student network applies a geometry-aware pooling operation, using its learned affinities to iteratively refine and denoise the initial features. This process yields a final representation that is both semantically rich and geometrically coherent.

✨ Key Features

• ⚡ Unrivaled Data Efficiency: Achieves or surpasses SOTA performance on major benchmarks (ScanNetV2, Matterport3D) while training on only ~1.5% of the data, eliminating the need for large-scale 3D annotations.
• 🎓 Novel Geometric Distillation: Introduces a teacher-student framework that distills purely geometric affinities from a 3D self-supervised model. This learns a class-agnostic prior to correct structural inconsistencies in 2D-lifted features.
• 🌍 Strong Generalization: The decoupled architecture provides robust zero-shot performance on long-tail benchmarks and excels in cross-dataset generalization, unlike methods that learn entangled geo-semantic representations.
• 🎯 Simple & Effective Purification: At inference, a lightweight Geometry-Guided Pooling module uses the learned affinities to denoise features, producing coherent and accurate segmentation maps.

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🛠️ Installation

For detailed setup instructions, please see the Installation Guide.

🚀 Usage

Data Preparation

• Input: Multi-view RGB-D images + 3D point clouds.
• Datasets supported: ScanNetV2, Matterport3D, and ScanNet200.
• Follow preprocessing scripts in scripts/preprocess.

Training GeoPurify

Run training with the curated subset (~1.5% of data):

sh run/train.sh --exp_dir=out/scannet --config=config/geopurify_scannet.yaml

Inference

Apply trained model for open-vocabulary 3D segmentation. Pretrained checkpoints are provided under:

• Matterport3D: result/matterport/model
• ScanNetV2: result/scannet/model

sh run/val.sh --exp_dir=out/scannet --config=config/geopurify_scannet.yaml --ckpt_name=geopurify.pth

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📊 Evaluation

Datasets

• ScanNetV2: 1,500 RGB-D scans.
• Matterport3D: 90 large-scale indoor scenes.
• ScanNet200: Long-tail benchmark emphasizing rare categories.

Metrics

• mIoU (mean Intersection-over-Union)
• mAcc (mean Accuracy)
• Foreground-mIoU / Foreground-mAcc (excluding wall/floor/ceiling).

Results

• ScanNetV2 (∼1.5% data): 55.1 mIoU / 72.5 mAcc
• Matterport3D: 40.2 mIoU / 62.4 mAcc.
• ScanNet200 (long-tail): 11.9 f-mIoU / 22.8 f-mAcc

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📦 Checkpoints

Pretrained checkpoints are available on Google Drive: 🔗 Download Here

Usage

• Matterport3D checkpoint: checkpoint/result/matterport/model/geopurify.pth

• ScanNetV2 checkpoint: checkpoint/result/scannet/model/geopurify.pth

📚 Citation

If you find this work useful, please cite:

@misc{dou2025geopurifydataefficientgeometricdistillation,
      title={GeoPurify: A Data-Efficient Geometric Distillation Framework for Open-Vocabulary 3D Segmentation},
      author={Weijia Dou and Xu Zhang and Yi Bin and Jian Liu and Bo Peng and Guoqing Wang and Yang Yang and Heng Tao Shen},
      year={2025},
      eprint={2510.02186},
      archivePrefix={arXiv},
      primaryClass={cs.CV},
      url={https://arxiv.org/abs/2510.02186},
}

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🙏 Acknowledgements

We thank the authors of Sonata, X-Decoder, and XMask3D for their excellent open-source contributions.

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📜 License

This project is licensed under the MIT License.