LASER: Layer-wise Scale Alignment for Training-Free Streaming 4D Reconstruction

Fuente: arXiv
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Autores principales: Ding, Tianye, Xie, Yiming, Liang, Yiqing, Chatterjee, Moitreya, Miraldo, Pedro, Jiang, Huaizu
Formato: Preprint
Publicado: 2025
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author Ding, Tianye
Xie, Yiming
Liang, Yiqing
Chatterjee, Moitreya
Miraldo, Pedro
Jiang, Huaizu
author_facet Ding, Tianye
Xie, Yiming
Liang, Yiqing
Chatterjee, Moitreya
Miraldo, Pedro
Jiang, Huaizu
contents Recent feed-forward reconstruction models like VGGT and $π^3$ achieve impressive reconstruction quality but cannot process streaming videos due to quadratic memory complexity, limiting their practical deployment. While existing streaming methods address this through learned memory mechanisms or causal attention, they require extensive retraining and may not fully leverage the strong geometric priors of state-of-the-art offline models. We propose LASER, a training-free framework that converts an offline reconstruction model into a streaming system by aligning predictions across consecutive temporal windows. We observe that simple similarity transformation ($\mathrm{Sim}(3)$) alignment fails due to layer depth misalignment: monocular scale ambiguity causes relative depth scales of different scene layers to vary inconsistently between windows. To address this, we introduce layer-wise scale alignment, which segments depth predictions into discrete layers, computes per-layer scale factors, and propagates them across both adjacent windows and timestamps. Extensive experiments show that LASER achieves state-of-the-art performance on camera pose estimation and point map reconstruction %quality with offline models while operating at 14 FPS with 6 GB peak memory on a RTX A6000 GPU, enabling practical deployment for kilometer-scale streaming videos. Project website: https://neu-vi.github.io/LASER/
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle LASER: Layer-wise Scale Alignment for Training-Free Streaming 4D Reconstruction
Ding, Tianye
Xie, Yiming
Liang, Yiqing
Chatterjee, Moitreya
Miraldo, Pedro
Jiang, Huaizu
Computer Vision and Pattern Recognition
Recent feed-forward reconstruction models like VGGT and $π^3$ achieve impressive reconstruction quality but cannot process streaming videos due to quadratic memory complexity, limiting their practical deployment. While existing streaming methods address this through learned memory mechanisms or causal attention, they require extensive retraining and may not fully leverage the strong geometric priors of state-of-the-art offline models. We propose LASER, a training-free framework that converts an offline reconstruction model into a streaming system by aligning predictions across consecutive temporal windows. We observe that simple similarity transformation ($\mathrm{Sim}(3)$) alignment fails due to layer depth misalignment: monocular scale ambiguity causes relative depth scales of different scene layers to vary inconsistently between windows. To address this, we introduce layer-wise scale alignment, which segments depth predictions into discrete layers, computes per-layer scale factors, and propagates them across both adjacent windows and timestamps. Extensive experiments show that LASER achieves state-of-the-art performance on camera pose estimation and point map reconstruction %quality with offline models while operating at 14 FPS with 6 GB peak memory on a RTX A6000 GPU, enabling practical deployment for kilometer-scale streaming videos. Project website: https://neu-vi.github.io/LASER/
title LASER: Layer-wise Scale Alignment for Training-Free Streaming 4D Reconstruction
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.13680