We address the problem of 3D rotation equivariance in convolutional neural
networks. 3D rotations have been a challenging nuisance in 3D classification
tasks requiring higher capacity and extended data augmentation in order to
tackle it. We model 3D data with multi-valued spherical functions and we
propose a novel spherical convolutional network that implements exact
convolutions on the sphere by realizing them in the spherical harmonic domain.
Resulting filters have local symmetry and are localized by enforcing smooth
spectra. We apply a novel pooling on the spectral domain and our operations are
independent of the underlying spherical resolution throughout the network. We
show that networks with much lower capacity and without requiring data
augmentation can exhibit performance comparable to the state of the art in
standard retrieval and classification benchmarks.

论文提出通过多值球面函数和在球谐域中实现球面上的准确卷积来解决 3D 卷积神经网络中的 3D 旋转等变性问题，进而提供了一种局部对称且通过平滑的频谱实现本地化滤波器的方法，同时还实现了一种用于谱域的新型池化技术，这些操作使得网络不需要过多的容量和数据增强即可在标准检索和分类基准测试中与现有的最先进性能相当。