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Domain Alignment Meets Fully Test-Time Adaptation
Proceedings of The 14th Asian Conference on Machine
Learning, PMLR 189:1006-1021, 2023.
Abstract
A foundational requirement of a deployed ML model is
to generalize to data drawn from a testing
distribution that is different from training. A
popular solution to this problem is to adapt a
pre-trained model to novel domains using only
unlabeled data. In this paper, we focus on a
challenging variant of this problem, where access to
the original source data is restricted. While fully
test-time adaptation (FTTA) and unsupervised domain
adaptation (UDA) are closely related, the advances
in UDA are not readily applicable to TTA, since most
UDA methods require access to the source
data. Hence, we propose a new approach, CATTAn, that
bridges UDA and FTTA, by relaxing the need to access
entire source data, through a novel deep subspace
alignment strategy. With a minimal overhead of
storing the subspace basis set for the source data,
CATTAn enables unsupervised alignment between source
and target data during adaptation. Through extensive
experimental evaluation on multiple 2D and 3D vision
benchmar ks (ImageNet-C, Office-31, OfficeHome,
DomainNet, PointDA-10) and model architectures, we
demonstrate significant gains in FTTA
performance. Furthermore, we make a number of
crucial findings on the utility of the alignment
objective even with inherently robust models,
pre-trained ViT representations and under low sample
availability in the target domain.