In recent years, semi-supervised learning has been widely explored and shows excellent data efficiency for 2D data. There is an emerging need to improve data efficiency for 3D tasks due to the scarcity of labeled 3D data. This paper explores how the coherence of different modalities of 3D data (e.g. point cloud, image, and mesh) can be used to improve data efficiency for both 3D classification and retrieval tasks. We propose a novel multimodal semi-supervised learning framework by introducing instance-level consistency constraint and a novel multimodal contrastive prototype (M2CP) loss. The instance-level consistency enforces the network to generate consistent representations for multimodal data of the same object regardless of its modality. The M2CP maintains a multimodal prototype for each class and learns features with small intra-class variations by minimizing the feature distance of each object to its prototype while maximizing the distance to the others. Our proposed framework significantly outperforms all the state-of-the-art counterparts for both classification and retrieval tasks by a large margin on the modelNet10 and ModelNet40 datasets.
Multi-task Multimodal Learning for Disaster Situation Assessment
During disaster events, emergency response teams need to draw up the response plan at the earliest possible stage. Social media platforms contain rich information which could help to assess the current situation. In this paper, a novel multi-task multimodal deep learning framework with automatic loss weighting is proposed. Our framework is able to capture the correlation among different concepts and data modalities. The proposed automatic loss weighting method can prevent the tedious manual weight tuning process and improve the model performance. Extensive experiments on a large-scale multimodal disaster dataset from Twitter are conducted to identify post-disaster humanitarian category and infrastructure damage level. The results show that by learning the shared latent space of multiple tasks with loss weighting, our model can outperform all single tasks.
- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- 2020 IEEE Conference on Multimedia Information Processing and Retrieval (MIPR)
- Page Range or eLocation-ID:
- 209 to 212
- Sponsoring Org:
- National Science Foundation
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