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This paper introduces a controlled subspace intervention framework to analyze how self-supervised Vision Transformers (ViTs) encode geometric information, addressing the limitations of linear probing that treats features as a black box. By employing Singular Value Decomposition (SVD) to decompose the weights of linear probes, the authors reveal that pre-training objectives significantly influence feature encoding, with DINOv2 aligning spatial features more effectively than Masked Autoencoders (MAE). The study uncovers that explicit geometric representations are compressible and that geometric precision is maximized at intermediate layers, providing insights for feature selection and lightweight decoder design.
Pre-training objectives shape how ViTs encode geometric information, revealing that some models can compress dense geometric signals without sacrificing performance.
We introduce a controlled subspace intervention framework to investigate how self-supervised Vision Transformers (ViTs) encode dense geometric information. While linear probing is widely used to assess geometric representations, it treats features as a black box, failing to disentangle the underlying topology. To address this issue, we decompose the weights of converged linear probes to isolate the low-rank subspaces containing explicit geometric signals using Singular Value Decomposition (SVD). Our perspective yields three key insights: (1) Pre-training objectives determine how features are encoded. DINOv2 aligns spatial features for efficient linear extraction, while Masked Autoencoders (MAE) tend to disperse these signals, requiring a broader spatial context. (2) Explicit geometric representations are highly compressible, suggesting dense predictive heads could potentially be constrained to low-rank subspaces with minimal performance loss. (3) The layer-wise task affinity suggests that geometric precision peaks at intermediate layers before yielding to semantic abstraction in the final layers. By connecting internal encoding mechanics with downstream performance, these findings provide a basis for effective feature selection and lightweight decoder design. The source code is available at https://github.com/Zhou-Weichen/Geosubprobe.