We tackle open-vocabulary 3D scene understanding by introducing a novel data generation pipeline and training framework. Our method addresses three critical requirements for effective training: precise 3D region segmentation, comprehensive textual descriptions, and sufficient dataset scale. By leveraging state-of-the-art open-vocabulary image segmentation models and region-aware Vision-Language Models (VLM), we develop an automatic pipeline that generates high-quality 3D mask-text pairs. Applying this pipeline to multiple 3D scene datasets, we create the Mosaic3D dataset, a dataset of over 30K annotated scenes with 5.6M mask-text pairs—significantly larger than existing datasets. Building upon this data, we propose Mosaic3D, a foundation model combining a 3D encoder trained with contrastive learning and a lightweight mask decoder for open-vocabulary 3D semantic and instance segmentation. Our approach achieves state-of-the-art results on open-vocabulary 3D semantic and instance segmentation tasks including ScanNet200, Matterport3D, and ScanNet++, with ablation studies validating the effectiveness of our large-scale training data.
@article{lee2025mosaic3d,
title={Mosaic3D: Foundation Dataset and Model for Open-Vocabulary 3D Segmentation},
author={Junha Lee and Chunghyun Park and Jaesung Choe and Frank Wang and Jan Kautz and Minsu Cho and Chris Choy},
journal={arXiv},
year={2025}
}