G3T Up! Gravity Aligned Coordinate Frames Simplify Pointmap Processing

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Hauptverfasser: Kani, Bharath Raj Nagoor, Snavely, Noah
Format: Preprint
Veröffentlicht: 2026
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author Kani, Bharath Raj Nagoor
Snavely, Noah
author_facet Kani, Bharath Raj Nagoor
Snavely, Noah
contents Modern feed-forward 3D reconstruction methods like VGGT predict pixel-aligned pointmaps in camera-centric coordinate frames. However, this choice of coordinate frame is not always optimal. We propose instead to predict pointmaps in upright, gravity-aligned frames that exploit strong structural cues present in many real-world scenes. Unlike camera-centric frames, gravity-aligned frames share a common vertical axis across viewpoints, reducing the rotational degrees of freedom needed to relate pointmaps to one another. To this end, we introduce the Gravity Grounded Geometry Transformer (G3T), fine-tuned from existing models on gravity-aligned 3D data. G3T produces highly accurate gravity-aware predictions, including upright pointmaps and camera-to-gravity poses. We further introduce G3T-Long, a submap-based incremental 3D reconstruction pipeline that leverages the reduced rotational degrees of freedom afforded by upright frames to achieve significantly improved reconstruction accuracy.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27372
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle G3T Up! Gravity Aligned Coordinate Frames Simplify Pointmap Processing
Kani, Bharath Raj Nagoor
Snavely, Noah
Computer Vision and Pattern Recognition
Modern feed-forward 3D reconstruction methods like VGGT predict pixel-aligned pointmaps in camera-centric coordinate frames. However, this choice of coordinate frame is not always optimal. We propose instead to predict pointmaps in upright, gravity-aligned frames that exploit strong structural cues present in many real-world scenes. Unlike camera-centric frames, gravity-aligned frames share a common vertical axis across viewpoints, reducing the rotational degrees of freedom needed to relate pointmaps to one another. To this end, we introduce the Gravity Grounded Geometry Transformer (G3T), fine-tuned from existing models on gravity-aligned 3D data. G3T produces highly accurate gravity-aware predictions, including upright pointmaps and camera-to-gravity poses. We further introduce G3T-Long, a submap-based incremental 3D reconstruction pipeline that leverages the reduced rotational degrees of freedom afforded by upright frames to achieve significantly improved reconstruction accuracy.
title G3T Up! Gravity Aligned Coordinate Frames Simplify Pointmap Processing
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.27372