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PointLLM: Empowering Large Language Models to Understand Point Clouds (2308.16911v3)

Published 31 Aug 2023 in cs.CV, cs.AI, and cs.CL

Abstract: The unprecedented advancements in LLMs have shown a profound impact on natural language processing but are yet to fully embrace the realm of 3D understanding. This paper introduces PointLLM, a preliminary effort to fill this gap, enabling LLMs to understand point clouds and offering a new avenue beyond 2D visual data. PointLLM understands colored object point clouds with human instructions and generates contextually appropriate responses, illustrating its grasp of point clouds and common sense. Specifically, it leverages a point cloud encoder with a powerful LLM to effectively fuse geometric, appearance, and linguistic information. We collect a novel dataset comprising 660K simple and 70K complex point-text instruction pairs to enable a two-stage training strategy: aligning latent spaces and subsequently instruction-tuning the unified model. To rigorously evaluate the perceptual and generalization capabilities of PointLLM, we establish two benchmarks: Generative 3D Object Classification and 3D Object Captioning, assessed through three different methods, including human evaluation, GPT-4/ChatGPT evaluation, and traditional metrics. Experimental results reveal PointLLM's superior performance over existing 2D and 3D baselines, with a notable achievement in human-evaluated object captioning tasks where it surpasses human annotators in over 50% of the samples. Codes, datasets, and benchmarks are available at https://github.com/OpenRobotLab/PointLLM .

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Citations (105)
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Summary

  • The paper introduces PointLLM, a novel framework that integrates a point cloud encoder with an LLM to combine geometric and textual data effectively.
  • The paper employs a two-stage training process with 730K point-text instruction pairs to align latent spaces and enhance multi-modal understanding.
  • The paper demonstrates that PointLLM outperforms 2D and 3D baselines in object classification and captioning, even surpassing human annotations on key benchmarks.

PointLLM: Empowering LLMs to Understand Point Clouds

The paper presents an innovative framework, PointLLM, which integrates LLMs with 3D point cloud data. This approach addresses the limitations of conventional LLMs, primarily their inability to effectively process and understand 3D visual data alongside traditional text-based data.

PointLLM leverages a point cloud encoder in conjunction with a powerful LLM to merge geometric, appearance, and linguistic information. By doing so, it enables the comprehension of colored 3D object point clouds grounded in human instructions. The model has been evaluated on two benchmarks: Generative 3D Object Classification and 3D Object Captioning, with assessments conducted via human evaluation, GPT-4/ChatGPT, and traditional metrics.

Methodology

The methodology introduces a novel dataset of 730K point-text instruction pairs, facilitating a two-stage training approach. The first stage involves aligning latent spaces, while the second focuses on instruction tuning. This approach ensures that PointLLM effectively integrates both visual and textual data, enhancing its performance across tasks demanding nuanced 3D perception.

The architecture comprises a pre-trained point cloud encoder, a projector for aligning point features to text space, and a LLM backbone. Their strategic integration enables PointLLM to generate coherent textual descriptions and classifications from 3D data inputs.

Performance and Evaluation

The paper presents significant performance improvements of PointLLM over established 2D and 3D baselines across both classification and captioning tasks. In particular, PointLLM demonstrated superiority in the Generative 3D Object Classification benchmark, as it efficiently processed unseen 3D data without retraining. Its prowess was further evident in 3D Object Captioning, where it outperformed human annotators on over half the samples according to human evaluation metrics. This indicates a level of detail and accuracy in object description that rivals manual annotations.

Implications and Future Directions

PointLLM signifies a marked step forward in multi-modal LLM research, successfully tackling the challenges associated with 3D structures like depth ambiguity and viewpoint dependencies that beset 2D models. Its ability to seamlessly integrate geometric and linguistic data suggests wide-ranging applications, including interactive 3D content creation and advanced robotics.

Future research could explore PointLLM’s potential in text-to-3D generation, capitalizing on its detailed captioning ability to enhance generative tasks. Advancements in efficiently training larger model variants or reducing hallucination rates without sacrificing precision are promising avenues for further development.

In conclusion, the paper outlines a solid framework for multi-modal LLMs engaging with 3D point clouds, highlighting both innovative technical approaches and superior performance metrics. It effectively opens up new possibilities for LLM applications in AI, thereby pushing the boundaries of multi-modal language processing.