Point-DAE: Denoising Autoencoders for Self-supervised Point Cloud Learning

Masked autoencoder has demonstrated its effectiveness in self-supervised point cloud learning. Considering that masking is a kind of corruption, in this work we explore a more general denoising autoencoder for point cloud learning (Point-DAE) by investigating more types of corruptions beyond masking. Specifically, we degrade the point cloud with certain corruptions as input, and learn an encoder-decoder model to reconstruct the original point cloud from its corrupted version. Three corruption families (i.e., density/masking, noise, and affine transformation) and a total of fourteen corruption types are investigated. Interestingly, the affine transformation-based Point-DAE generally outperforms others (e.g., the popular masking corruptions), suggesting a promising direction for self-supervised point cloud learning. More importantly, we find a statistically significant linear relationship between task relatedness and model performance on downstream tasks. This finding partly demystifies the advantage of affine transformation-based Point-DAE, given that such Point-DAE variants are closely related to the downstream classification task. Additionally, we reveal that most Point-DAE variants unintentionally benefit from the manually-annotated canonical poses in the pre-training dataset. To tackle such an issue, we promote a new dataset setting by estimating object poses automatically. The codes will be available at \url{https://github.com/YBZh/Point-DAE.}