In the paper of the winners of the Galaxy Zoo Kaggle Competiton there is an (at least for me) unusual step: Viewpoint extraction. It covers a kind of data augmentation where they crop and rotate/flip essential parts of the images-to-be classified. How does it differ from the usual data augmentation (which is also applied in their pipeline)? I am a bit confused what is the difference...
What is Viewpoint extraction in case of image preprocessing for classification?
image classification;kaggle