Contrastive Point Cloud Pretraining for Enhanced Transformers

Transformers, although first designed for sequence processing, can also handle unordered sets like point cloud data. Additionally, contrastive pretraining has emerged as a successful technique in image processing but remains unexplored for point cloud data. We develop and integrate a new point cloud pretraining technique inspired by the Simple Framework for Contrastive Learning (SimCLR) into the Set Transformer (ST) and Point Cloud Transformer (PCT) architectures and explore model performance using a novel 3D body scan dataset and the canonical datasets ShapeNet and ModelNet. For the 3D body scan dataset, this integration boosts initial training performance and maintains overall higher performance for classification tasks, and demonstrates better stability/convergence for regression tasks in comparison to non-pretrained (Naïve] counterparts. Furthermore, experiments examining strong generalization (relative performance on previously unseen classes) show improvement for pretrained models compared to Naïve models. Consistent benefits across tasks and data sets are observed based on additional experiments performed on the ShapeNet core dataset. Overall, we show how contrastive pretraining for point cloud data is a viable strategy for improving the performance of Transformers on downstream tasks and accelerating the training process.