MMVAE+: Enhancing the Generative Quality of Multimodal VAEs without Compromises

Multimodal VAEs have recently gained attention as efficient models for weakly-supervised generative learning with a large number of modalities. However, all existing variants of multimodal VAEs are affected by a non-trivial trade-off between generative quality and generative coherence. We focus on the mixture-of-experts multimodal VAE (MMVAE), which achieves good coherence only at the expense of sample diversity and a resulting lack of generative quality. We present a novel variant of the MMVAE that improves its generative quality, while maintaining high semantic coherence. For this, shared and modality-specific information is modelled in separate latent subspaces. In contrast to previous approaches with separate subspaces, our model is robust to changes in latent dimensionality and regularization hyperparameters. We show that our model achieves both good generative coherence and high generative quality in challenging experiments, including more complex multimodal datasets than those used in previous works.