Abstract
In recent years, there has been an explosion of 2D vision models for numerous tasks such as semantic segmentation, style transfer or scene editing, enabled by large-scale 2D image datasets. At the same time, there has been renewed interest in 3D scene representations such as neural radiance fields from multi-view images. However, the availability of 3D or multiview data is still substantially limited compared to 2D image datasets, making extending 2D vision models to 3D data highly desirable but also very challenging. Indeed, extending a single 2D vision operator like scene editing to 3D typically requires a highly creative method specialized to that task and often requires per-scene optimization. In this paper, we ask the question of whether any 2D vision model can be lifted to make 3D consistent predictions. We answer this question in the affirmative; our new Lift3D method trains to predict unseen views on feature spaces generated by a few visual models (i.e. DINO and CLIP), but then generalizes to novel vision operators and tasks, such as style transfer, super-resolution, open vocabulary segmentation and image colorization; for some of these tasks, there is no comparable previous 3D method. In many cases, we even outperform state-of-the-art methods specialized for the task in question. Moreover, Lift3D is a zero-shot method, in the sense that it requires no task-specific training, nor scene-specific optimization.
Overview
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Lift3D introduces a framework that transforms pre-trained 2D vision models into capable 3D prediction tools, enabling view-consistent predictions across multiple scenes.
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The method relies on refining and projecting intermediate feature maps from 2D models through advanced rendering techniques, achieving high-quality 3D outputs.
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Experimental results show Lift3D's effectiveness in various 3D vision tasks such as semantic segmentation and style transfer, comparing favorably to existing specialized methods.
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Lift3D's zero-shot capability to adapt to different scenes and tasks without the need for specific training defines a new direction for integrating 2D and 3D vision models.
Advanced 3D Predictions with Lift3D: Transforming 2D Vision Models to 3D
Introduction
The progression in 2D image understanding has seen remarkable advancements owing to the development of comprehensive image datasets and the innovation in neural network architectures. This has contributed significantly to achievements in diverse tasks such as semantic segmentation, style transfer, and scene editing. However, the application of these advancements to 3D understanding has been throttled by the scarcity of large, well-labeled multi-view image datasets. This limitation prompts a crucial inquiry: can we extend the prowess of 2D vision models to interpret and manipulate 3D data consistently across multiple views?
In response to this, the paper introduces Lift3D, a novel framework designed to elevate any pre-trained 2D vision model into the 3D domain, enabling it to produce view-consistent predictions. By emphasizing on a scene and operator-agnostic approach, Lift3D showcases remarkable flexibility, allowing it to adapt to various downstream tasks or scenes without the need for additional adjustments. Notably, its ability to resolve inconsistencies in multi-view predictions sets it apart, offering significant contributions to the fields of open vocabulary segmentation and text-driven scene editing.
Method Overview
Lift3D leverages the intermediate feature maps generated by 2D operators, refining and propagating these through a cleverly designed algorithm to achieve smooth and consistent predictions across views. It encapsulates this process within a pipeline that synthesizes novel view feature maps from given multi-view images and their corresponding 2D predictions. This process is anchored on image-based rendering principles and volume rendering techniques, enabling Lift3D to interpolate novel views in feature spaces generated by pre-trained 2D visual models.
The intricate architecture of Lift3D is conjured under the guidance of existing novel view synthesis techniques, which learn to aggregate pixels with epipolar constraints to synthesize novel views. By treating dense features as colors, Lift3D manages to interpolate features across multiple views, subsequently utilizing the decoder from the pre-trained 2D model to unveil the final 3D predictions.
Experiments and Results
Lift3D’s prowess was put to the test across various 3D vision tasks, including semantic segmentation, style transfer, and scene editing, producing outcomes comparable to, and at times surpassing, methods specialized for these tasks. A noteworthy feature of Lift3D is its zero-shot capability, requiring no scene-specific or operator-specific training. This encapsulates the novelty and potential of Lift3D in harnessing the capacity of 2D vision models for 3D applications effectively.
The experiments conducted validate Lift3D’s theoretical premise, demonstrating its exceptional ability to generalize across different feature backbones and tasks. Its performance against state-of-the-art methods in semantic segmentation, and its contribution to pioneering 3D extensions of 2D vision operations like image colorization and open vocabulary segmentation, underscore its practical significance.
Conclusions and Implications
Lift3D presents a groundbreaking approach to bridging the gap between 2D and 3D vision models. Its unique ability to produce view-consistent 3D predictions from any 2D vision model without requiring additional training or optimization marks a significant stride in the realm of 3D scene understanding.
The implications of this research are profound, offering a scalable solution to the challenge of data scarcity in 3D vision. By making it feasible to extend the functionalities of 2D models to 3D contexts universally, Lift3D opens new avenues for research and applications in autonomous driving, robotics, and beyond.
Future research might explore the extension of Lift3D's capabilities to handle more complex 3D representations and interactions, potentially leading to more comprehensive 3D understanding systems. The evolution of Lift3D and similar frameworks will undoubtedly play a pivotal role in the fusion of 2D and 3D vision technologies, driving forward the boundaries of what is achievable in the realm of artificial intelligence and computer vision.
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