“…As the very start in 3D FER, the data description is the most fundamental and crucial. A simple but widely used way of the data description in the literature on 3D FER is the vectorization (See, e.g., [24,25,31,37,38,45,46,49,55,56]). However, the main drawback that vectorization suffers is the loss of the internal structure information of the data samples in which potential or inherent sparsity may hidden, and hence the dimensionality curse comes along by dismissing these favorable structural properties.…”