PUnDA: Probabilistic Unsupervised Domain Adaptation for Knowledge Transfer Across Visual Categories
This paper introduces a probabilistic latent variable model to address unsupervised domain adaptation problems. Specifically, we tackle the task of categorization of visual input from different domains by learning projections from each domain to a latent (shared) space jointly with the classifier in the latent space, which simultaneously minimizes the domain disparity while maximizing the classifier's discriminative power. Furthermore, the non-parametric nature of our adaptation model makes it possible to infer the latent space dimension automatically from data. We also develop a novel regularized Variational Bayes (VB) algorithm for efficient estimation of the model parameters. We compare the proposed model with the state-of-the-art methods for the tasks of visual domain adaptation using both handcrafted and deep-net features. Our experiments show that even with a simple softmax classifier, our model outperforms several state-of-the-art methods that take advantage of more sophisticated classification schemes.