arXiv Machine Learning By Joshua Williamson, Niall Jeffrey, Lorne Whiteway

Learning without relearning physical symmetry: an SO(3)-equivariant convolutional network (CNN) on the sphere

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The paper introduces a novel SO(3)-equivariant convolutional neural network designed for data on the sphere, specifically using the Hierarchical Equal Area isoLatitude Pixelization (HEALPix). By employing steerable filters, parallel transport, and spin-weighted features, the architecture guarantees exact equivariance and avoids the need for the network to learn spherical symmetry from data. Benchmarks show the model achieves percent-level SO(3)-invariance error and outperforms existing methods in dense gradient regression, cosmic microwave background foreground removal, and denoising tasks.

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